基于神经PID网络的串级调节系统研究

本文提出了一种神经PID网络控制器，并利用它构成串级调节系统。在给出网络结构和计算公式的基础上，进行了计算机仿真。仿真结果表明，神经PID网络控制器构成的串级调节系统具有良好的动态和静态性能及很强的抗扰能力。     

The arterioportal fistula syndrome: clinicopathologic features, diagnosis, and therapy

BACKGROUND & AIMS: Arterioportal fistulas (APFs) are rare vascular disorders of the mesenteric circulation. The aim of this study was to determine the etiology, anatomical location, and main symptom at presentation of APFs, and analyze the various modes of treatment. METHODS: The etiology, clinical presentation, radiographs, and treatment of 12 patients with APFs are reported in detail, and another 76 cases published since 1980 are reviewed. RESULTS: APFs result from trauma (n = 25, 28%), iatrogenic procedures (n = 14, 16%), congenital vascular malformations (n = 13, 15%), tumor (n = 13, 15%), aneurysm (n = 12, 14%), and other causes (n = 11, 12%). The origin of APFs is the hepatic artery in the majority of patients (n = 56, 65%). The main symptoms at presentation are lower or upper gastrointestinal bleeding (n = 29, 33%), ascites (n = 23, 26%), heart failure (n = 4.5%), or diarrhea (n = 4.5%). Radiological intervention provides definitive treatment in 42% (n = 33) of patients, whereas the remainder are treated by surgery alone (n = 27, 31%) or a combination of radiological intervention and surgery (n = 8, 9%). CONCLUSIONS: APFs result in a protean syndrome variously combining portal hypertension and other hemodynamic imbalances (heart failure, intestinal ischemia). Single or multiple interventional radiological procedures using arterial and/or venous approaches allow definitive treatment of most APFs. With increasing technological advances, it is anticipated that surgery will only be indicated in rare instances after failure of radiological intervention(s).     

Elastic-plastic indentation stress fieldsusing the finite-element method

The finite-element method is used to model the elastic-plastic indentation response of a flat extensive specimen for the case of a spherical indenter. The work highlights several interesting finite-element modelling techniques and provides insight into the physical processes involved in elastic-plastic indentation of certain structural ceramics. Full details of the stress distribution are given and compared with the results of elastic formulae. This work has particular application to the modelling of physical phenomena of deformation in ceramic materials in machining, wear, bearings and hardness testing. This revised version was published online in November 2006 with corrections to the Cover Date.     

The progression of chronic renal disease: immunological, nutritional and intrinsic renal mechanisms

The majority of patients with any initial renal insult show progression of renal damage over time. The histological end-result is often the same, whatever the initial lesion, and consists of an increase in extracellular matrix (ECM) and ultimately glomerulosclerosis. The clinical rate of progression correlates mainly with the degree of interstitial, rather than with that of glomerular damage. The main culprits for the ultimate interstitial damage and the rate of progression of renal disease, are the type and degree of the initial (e.g. immunological) insult and the magnitude of the proteinuria. Hypertension (intraglomerular) is an independent risk factor. Control of hypertension with angiotension converting enzyme (ACE) inhibitors or angiotensin II (AII) receptor blockers, reduction of protein and fat intake, anti-oxidative therapy and a variety of experimental measures reduce the progression of renal damage in animal experiments. Some of these interventions have also been shown to be beneficial in a number of controlled clinical studies, in well-defined renal disease entities in humans. These new data provide insight into the pathogenesis of chronic renal damage and raise the hope that in the not too far future, effective strategies can be devised to attenuate the progression of acquired renal disease.     

CO2 laser surgery in osteomyelitis

Spirituality is a critical component of the holistic mind-body-spirit model embraced by Hospice. Hospice chaplains, as part of the caregiving team, must understand their abilities and limitations in providing spiritual guidance to others who may differ in religious and spiritual beliefs.     

Characterization of aluminum hydroxide particles from the Bayerprocess using neural network and Bayesian classifiers

An automatic process of isolating and characterizing individual aluminum hydroxide particles from the Bayer process in scanning electron microscope gray-scale images of samples is described. It uses image processing algorithms, neural nets and Bayesian classifiers. As the particles are amorphous and different greatly, there were complex nonlinear decisions and anomalies. The process is in two stages; isolation of particles, and classification of each particle. The isolation process correctly identifies 96.9% of the objects as complete and single particles after a 15.5% rejection of questionable objects. The sample set had a possible 2455 particles taken from 384 256x256-pixel images. Of the 15.5%, 14.2% were correctly rejected. With no rejection the accuracy drops to 91.8% which represents the accuracy of the isolation process alone. The isolated particles are classified by shape, single crystal protrusions, texture, crystal size, and agglomeration. The particle samples were preclassified by a human expert and the data were used to train the five classifiers to embody the expert knowledge. The system was designed to be used as a research tool to determine and study relationships between particle properties and plant parameters in the production of smelting grade alumina by the Bayer process.     

The cross product of interconnection networks

We study the cross product as a method for generating and analyzing interconnection network topologies for multiprocessor systems. Consider two interconnection graphs G₁ and G₂ each with some established properties such as symmetry, low degree and diameter, scalability, simple optimal routing, recursive structure (partitionability), fault tolerance, existence of node-disjoint paths, low cost embedding, and efficient broadcasting. We investigate and evaluate the corresponding properties for the cross product of G₁ and G₂ based on the properties of G₁ and those of G₂. We also give a mathematical characterization of product families of graphs which are closed under the cross product operation. This investigation is useful in two ways. On one hand, it gives a new tool for further studying some of the known interconnection topologies, such as the hypercube and the mesh, which can be defined using the cross product operation. On the other hand, it can be used in defining and evaluating new interconnection graphs using the cross product operation on known topologies     

Single-dose versus multiple instillations of epirubicin as prophylaxis for recurrence after transurethral resection of pTa and pT1 transitional-cell bladder tumours: a prospective, randomized controlled study

OBJECTIVE: To compare single-dose and multiple instillations of epirubicin in the chemoprophylaxis of superficial bladder tumours. PATIENTS AND METHODS: In a prospective randomized and controlled study, 168 evaluable patients were assigned to three groups after transurethral resection of bladder tumour (TURBT) and histological confirmation of its superficial nature (pTa and pT1). The groups were comparable for tumour stage, grade and other tumour characteristics. In group 1, patients received a single dose of 50 mg epirubicin in 50 mL normal saline immediately after TURBT; group 2 received 50 mg epirubicin in 50 mL normal saline 1-2 weeks after TURBT and the instillations were repeated for 8 weeks and thereafter monthly to complete one year of treatment: group 3 (control group) received no adjuvant therapy after TURBT. The patients were assessed by cysto-urethroscopy, urine cytology and DNA flow cytometry 8 weeks after resection and then every 3 months during the first 2 years and 6 monthly thereafter during the next 2 years. Intravenous urography was performed annually and when otherwise indicated. RESULTS: The recurrence rate was significantly lower in the patients treated with epirubicin than in the control group (24, 25 and 52%, respectively; P < 0.001). In those receiving epirubicin, the rates of recurrence were statistically comparable (P = 0.9). Patients who had a large tumour burden showed slightly lower recurrence rates with single-dose epirubicin than with delayed maintenance therapy but the difference was statistically insignificant. Patients with a history of bladder tumours before treatment had lower recurrence rates with maintenance treatment than with a single dose (34.6 and 22.6% in groups 1 and 2, respectively); again this difference was statistically insignificant. Patients with grade 3 tumours showed a marginal difference in favour of maintenance therapy. The rates of progression amongst the three groups were 5.5, 3.4 and 9.3%, respectively, with no significant differences. The overall toxicity rates were comparable in the two treated groups (22 and 25%). CONCLUSION: With the possible exception of grade 3 tumours, single-dose immediate epirubicin is as effective as delayed maintenance therapy, with the advantage of being more cost-effective.     

Ability of pediatric residents to read critically research papers]

PURPOSE: To compare the response rates, toxicities and survival durations of elderly patients (70 years of age or more) with those of younger patients (less than 70 years of age) with non-small-cell lung cancer (NSCLC) treated with cisplatin-based chemotherapy. PATIENTS AND METHODS: We analyzed retrospectively the data of 203 assessable patients entered on a prospective randomized trial of cisplatin-based combination chemotherapy. Chemotherapy consisted of three dosage regimens: (1) vindesine and cisplatin (VP); (2) mitomycin, vindesine and cisplatin (MVP); or (3) etoposide and cisplatin alternating with vindesine and mitomycin (EP/VM). RESULTS: A greater proportion of elderly patients had localized disease and more squamous cell carcinoma than non-elderly patients. The overall response rates were 44% in the elderly group and 28% in the non-elderly group. In the EP/VM arm, the response rate was significantly better in the elderly group than in the non-elderly group. The frequency of grade 4 leukocytopenia in the MVP and EP/VM arms in the elderly group was significantly greater than in the non-elderly group (P < 0.05). No differences were found in nonhematological toxicities between the two groups. There was no difference in overall survival between the groups. CONCLUSION: Elderly patients treated with mitomycin-containing regimens have higher hematologic toxicities than younger patients. The results of this study are consistent with the previously reported pharmacologic data on mitomycin suggesting altered pharmacokinetics in elderly patients. The improved response rate in the elderly patients was probably because more elderly patients had earlier disease, squamous cell carcinoma and better performance status. Cisplatin-based chemotherapy was tolerable for most elderly NSCLC patients with good performance status.     

Comparisons of pulmonary and sinonasal lesions in patients with cystic fibrosis. Evaluation using computerized tomography

INTRODUCTION: Cystic fibrosis is a recessive genetic systemic exocrinopathy caused by a variety of mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). The disease is characterized by alterations of the secretions, which become thickened and viscous. Both the paranasal sinuses and the lung parenchyma are involved in all cases. The aim of this study was to assess a correlation between the rhinosinusal and lung parenchyma changes in cystic fibrosis patients. MATERIAL AND METHODS: Eighteen patients (11 men and 7 women, age range: 8 to 22 years) were examined with chest HRCT and sinonasal low dose CT. Lung symptoms were found in all patients; 13 of them, also affected with rhinosinusal symptoms, had been examined with ENT and nasal endoscopy. The other 5 patients, without rhinosinusal symptoms and previously examined with ENT, were evaluated as control group. Chest CT was performed with the high-resolution technique, 2 mm slice thickness and 10 mm table feed. Rhinosinusal CT was performed with the low dose technique, acquiring contiguous 2-4 mm thickness coronal sections. The CT patterns were analyzed by two radiologists and scored as slight, medium and diffuse involvement of both districts. RESULTS: No statistically significant correlation between lung and sinonasal damage was found in our study. Parenchymal lung involvement appeared more severe than sinonasal involvement in 14/18 patients. The retention of secretions in the paranasal sinuses, even if limited, was demonstrated in all symptomatic and asymptomatic patients. CONCLUSIONS: The absence of correlation between pulmonary and sinonasal damage and more generally, the different severity of cystic fibrosis can be caused by different allele mutations of the cystic fibrosis transmembrane conductance regulator gene, the most frequent of which is Delta F-508.