SLH电源拓扑及其开环系统的负载适应性—SLH功率变换技术及应用(三)

在 “SLH 连载之一、二”从理论角度阐明开关线性复合(SLH)电源因高阻输出特性而获强鲁棒性的基础上，结合其典型拓扑的实践及效果，揭示了SLH开环系统对负载参数变化和多类负载呈现自适应能力的内在原因，廓清了相关学术概念，为 “连载之一、二”提供了实验依据。     

Scalable and fault‐tolerant key agreement protocol for dynamic groups

With the widespread use of the Internet, the popularity of group communication‐based applications has grown considerably. Since most communications over the Internet involve the traversal of insecure networks, basic security services are necessary for these collaborative applications. These security services can be facilitated if the authorized group members share a common secret. In such distributed applications, key agreement protocols are preferred to key distribution protocols. In the past two decades, there have been many proposals for key agreement protocols. Most of these protocols are not efficient and limit the size of the underlying group. In this paper, we consider the scalability problem in group key agreement protocols. We propose a novel framework based on extension of the Diffie–Hellman key exchange protocol. The efficiency of our protocol comes from the clustering of the group members, where the common session key is established collaboratively by all participants. We present the auxiliary protocols needed when the membership changes. We show that our protocol is superior in complexity in both communication and computation overheads required to generate the session key. Copyright © 2006 John Wiley & Sons, Ltd.     

Enhancement of tumor killing using a combination of tumor immunization and HSV-tk suicide gene therapy

Tumor cells genetically modified with the herpes simplex virus thymidine kinase (HSV-tk) gene in combination with ganciclovir (GCV) demonstrate a "bystander effect". Previous attempts to enhance the bystander tumor killing by combining cytokine genes with HSV-tk/GCV have met with varying results. The present study was designed to determine the effects of tumor immunization in combination with HSV-tk gene-modified tumor cells and GCV on tumor killing and to determine if the bystander tumor killing could be enhanced. Tumor-bearing mice immunized with syngeneic tumor (KBALB) prior to treatment with an i.p. injection of xenogeneic HSV-tk gene-modified tumor cells (PA-1STK) had prolonged animal survival (group 4, 56.4 days). In contrast, unimmunized tumor-bearing mice (group 2) or tumor-bearing mice immunized to the xenogeneic PA-1STK tumor cells (group 5) showed a mean survival of about 27 days after receiving an i.p. injection of PA-1STK cells and GCV. Control groups, which were either not immunized and did not receive HSV-tk cells (group 1) or immunized but treated only with GCV (group 3) showed short survival (16-18 days). Analysis of tumors for cytokine mRNA expression revealed increased TNF-alpha and IL-1alpha mRNA expression in group 4 mice. Furthermore, IL-2 mRNA expression was detectable on days 2 and 4 only in group 4 mice. Immunophenotypic analysis for tumor-infiltrating lymphocytes demonstrated an increase in macrophage (4%, p = 0.0001) and T cells (1.8%, p < 0.001) in group 4 mice with an enhanced T-cell response as compared with mice from groups 1, 2 and 3. Our results demonstrate that tumor immunization combined with HSV-tk/GCV treatment results in increased animal survival with enhanced immune response. Furthermore, the cytokine milieu observed in the present study can modulate the tumor micro-environment in vivo from one that is immunosuppressive to one that is immune-stimulatory.     

Experimental evaluation of space/frequency/polarization diversityin the indoor wireless channel

A series of experiments that were conducted to evaluate the relative merits of frequency, space, and polarization diversities in indoor portable radio channels at 900 MHz are described. Unmodulated tones were used to probe the channel in a typical university work environment. The statistics of the signal envelopes were analyzed to determine the correlation of the field strengths when the signals are separated in space, frequency or polarization. According to the results presented here, the performance of a narrowband system (<200 kHz) at 900 MHz could greatly benefit from a frequency diversity scheme provided that the separation between the two frequencies is greater than approximately 5 MHz. Similarly, the advantage of space diversity is found significant when the two antennas are spaced by 3/4 wavelength or more. Co-polarized and cross-polarized signals are nearly uncorrelated and their relative field strengths differ by less than 2 dB in most locations     

Response of the hypothalamic neurons to stimulation of the vestibular nerve and lateral vestibular nucleus in rabbits

Effects of single, double, and rhythmic stimulation upon hypothalamic neurons responding to the 1st excitatory phase of lateral vestibular nucleus stimulation, were studied. The data obtained show that activation of some hypothalamic neurons following stimulation of the lateral vestibular nucleus has a monosynaptic character. The findings suggest that ascending afferents from the lateral vestibular nucleus to the hypothalamus pass via oligo- as well as polysynaptic pathways.     

Congenital abnormalities in Brazilian children associated with misoprostol misuse in first trimester of pregnancy

BACKGROUND: Misoprostol is commonly used to induce abortion in Brazil, and in other countries in South and Central America where abortions are illegal. However, misoprostol is not very effective in inducing abortions, and exposure to the drug in utero can cause abnormalities in the fetus. We aimed to define the common phenotypical effects of exposure to the drug. METHODS: We studied 42 infants from S?o Paulo, Brazil, who were exposed to misoprostol during the first 3 months of gestation, and then born with congenital abnormalities. We interviewed each of the infants' mothers to find out about misoprostol exposure and dosage. Each infant was physically examined by a geneticist or a neuropaediatrician. FINDINGS: 17 of the infants had equinovarus with cranial-nerve defects. Ten children had equinovarus as part of more extensive arthrogryposis. The most distinctive phenotypes were arthrogryposis confined to the legs (five cases) and terminal transverse-limb defects (nine cases) with or without Mobius sequence. The most common dose of misoprostol taken was 800 microg (range 200-16000 microg). INTERPRETATION: Deformities attributed to vascular disruption were found in these children. We suggest that the uterine contractions induced by misoprostol cause vascular disruption in the fetus, including brain-stem ischaemia. Information on the effects of taking misoprostol during pregnancy should be made more widely available, to dissuade women from misusing the drug.     

New protein genetic studies in six Amazonian Indian populations

A total of 732 individuals affiliated with six Amazonian Indian populations were variously studied in relation to 26 protein genetic systems. Eleven of them were found to be monomorphic in these groups, in accordance with previous investigations. Similarities and dissimilarities (the latter involving the Rh, Duffy, haptoglobin and transferrin systems) were observed in relation to earlier investigations in four of these populations (Galibi, Palikour, Mundurucu and Tenharim). A dimeric, cathodal variant of albumin was found among two Galibi subjects, and the fairly common occurrence of CP* ACAY among some South American Indian populations was confirmed. The results in the six populations were compared with those from 29 others. When relationships are searched for among tribes of the same linguistic group, the factor that seems to be most influential is geographical localization, an exception being the pattern observed among the Cayapo subgroups. The latter shows genetic differences of the same level of magnitude as those observed among Ge-speaking tribes.     

Regulation of Sos activity by intramolecular interactions

The guanine nucleotide exchange factor Sos mediates the coupling of receptor tyrosine kinases to Ras activation. To investigate the mechanisms that control Sos activity, we have analyzed the contribution of various domains to its catalytic activity. Using human Sos1 (hSos1) truncation mutants, we show that Sos proteins lacking either the amino or the carboxyl terminus domain, or both, display a guanine nucleotide exchange activity that is significantly higher compared with that of the full-length protein. These results demonstrate that both the amino and the carboxyl terminus domains of Sos are involved in the negative regulation of its catalytic activity. Furthermore, in vitro Ras binding experiments suggest that the amino and carboxyl terminus domains exert negative allosteric control on the interaction of the Sos catalytic domain with Ras. The guanine nucleotide exchange activity of hSos1 was not augmented by growth factor stimulation, indicating that Sos activity is constitutively maintained in a downregulated state. Deletion of both the amino and the carboxyl terminus domains was sufficient to activate the transforming potential of Sos. These findings suggest a novel negative regulatory role for the amino terminus domain of Sos and indicate a cooperation between the amino and the carboxyl terminus domains in the regulation of Sos activity.     

Endometrial polyps: a comparison study of patients receiving tamoxifen with two control groups

OBJECTIVES: To provide a review of the unique features of both Hodgkin's and non-Hodgkin's lymphoma in pediatric and geriatric patient populations. Treatment approaches and nursing care interventions at the extremes of age will be discussed. DATA SOURCES: Review articles, research studies, and book chapters. CONCLUSIONS: Lymphoma is a highly heterogeneous malignancy whose classification and management have undergone significant evolution. Of particular concern has been lymphoma's prevalence and treatment at the extremes of age. Appropriate treatment by age and subtype remains controversial. IMPLICATIONS FOR NURSING PRACTICE: The nursing care of pediatric and geriatric patients with lymphoma presents numerous challenges in education, symptom management, and supportive care.