计算机病毒的计算复杂度问题

计算机病毒对计算机系统及软件造成各种各样的损害,除了一些常见的损害,例如删除数据或程序、修改系统信息以外,它们还造成一些非破坏性的影响,例如消耗大量的存贮及时间。这个问题涉及到计算机病毒的计算复杂度。文章初步探讨计算机病毒的计算复杂度问题,从数学上证明两个基本结论：存在计算机病毒,它的传染过程具有任意大计算复杂度;存在计算机病毒,被感染程序的执行过程具有任意大的计算复杂度。除此而外,文章简要讨论计算机病毒检测过程的计算复杂度问题。     

采动影响区煤层动态含气量数值模拟

煤矿采动影响区是地面煤层气开发或井下瓦斯抽放的有利部位。基于矿井瓦斯工作实践,划分了煤矿采动影响区类型,阐述了采动影响区煤层动态含气量的数值模拟方法,并以阳煤集团二矿为例对采动影响区内煤层动态含气量进行了估算。     

Severe liver failure due to influenza A infection in a hemodialysis patient

Patients with influenza infection most commonly present with upper and occasionally lower respiratory tract symptoms. However, extrapulmonary presentations such as hepatitis are infrequently observed. We report a case of a hemodialysis patient with influenza A infection who presented with severe hepatitis and liver failure, while his respiratory symptoms were mild. It is important to recognize influenza infection as an unexplained cause of hepatitis and liver failure. In our case, liver failure resolved with supportive treatment.     

Outdoor, but not indoor, nitrogen dioxide exposure is associated with persistent cough during the first year of life

Background and aims

Because their lungs and immune system are not completely developed, children are more susceptible to respiratory disease and more vulnerable to ambient pollution. We assessed the relation between prenatal and postnatal nitrogen dioxide (NO₂) levels and the development of lower respiratory tract infections (LRTI), wheezing and persistent cough during the first year of life.

Methods

The study population consisted of 352 children from a birth cohort in Valencia, Spain. Prenatal exposure to NO₂, a marker of traffic related air pollution was measured at 93 sampling sites spread over the study area during four different sampling periods of 7 days each. It was modeled for each residential address through land use regression using the empirical measurements and data from geographic information systems. Postnatal exposure was measured once inside and outside each home using passive samplers for a period of 14 days. Outcomes studied were any episode of LRTI during the child's first year of life diagnosed by a doctor (bronchitis, bronchiolitis or pneumonia), wheezing (defined as whistling sounds coming from the chest), and persistent cough (more than three consecutive weeks). Outcomes and potential confounders were obtained from structured questionnaires. Multiple logistic regression was used to identify associations.

Results

The cumulative incidence (CI) at first year of life was 30.4% for LRTI (23.0% bronchiolitis, 11.9% bronchitis and 1.4% pneumonia), 26.1% for wheezing and 6.3% for persistent cough. The adjusted odds ratio (95% confidence interval) per 10 μg/m³ increment in postnatal outdoor NO₂ concentration was 1.40 (1.02-1.92) for persistent cough. We also found some pattern of association with LRTI, bronchiolitis, bronchitis, wheezing and persistent cough in different prenatal periods, although it was not statistically significant.

Conclusions

Our results indicate that exposure to outdoor, but not indoor, NO₂ during the first year of life increases the risk of persistent cough.     

Removing indoor particles using portable air cleaners: Implications for residential infection transmission

Reducing indoor exposure to influenza particles can be an important strategy to manage residential infections. Many portable air cleaning (PAC) technologies are currently employed in residential environments but very little research has been performed to evaluate and compare their performance in terms of particle removal associated with influenza. This study evaluates the effectiveness of portable air cleaners at removing airborne NaCl particles as an analogue to the influenza virus and applies the results to an IAQ mass balance model to evaluate the performance in controlling residential exposures and mitigating infection risks. Various devices representing different PAC technologies were tested using a pull down particle challenge in a full scale stainless steel chamber. Particle generation and measurement were conducted using a 6-jet atomizer and a paired aerodynamic particle sizer (APS)-scanning mobility particle sizer (SMPS), respectively. PAC incorporating HEPA filtration, electrostatic precipitation, ion generation and electret filtration were tested. We found that particle exposures released during a cough or sneeze event in a typical Quebec City residential room in Canada can significantly be reduced using HEPA, electrostatic precipitation and electret filtration PACs when compared with a situation where no PAC is being used. Modelling analysis demonstrates that the use of these PACs can mitigate the risks of influenza infection via airborne route for a caregiver or a spouse sharing the same room. The implications of this study are significant considering low ventilation rates of Quebec City residences.     

外照射急性放射病合并感染的防治

外照射急性放射病的主要致死原因之一是严重感染,预防和控制感染是救治急性放射病的关键。本文从外照射急性放射病合并感染的防治方面介绍其发病机制、临床表现、预防和救治措施以及其预后转归的研究现状。     

楔形桩的工作性能及应用研究

通过介绍楔形桩的受力机理 ,指出楔形桩不同于一般桩基 ,其楔形构造改变了桩周土的天然结构状态 ,利于发挥桩土的共同作用 ,提高了其承载力。介绍并总结了现有楔形桩承载力计算公式及按其计算所出现偏差的原因。并分析了楔形桩承载力与几何尺寸的一般关系     

屠宰生猪巴氏杆菌与未知菌混合感染的分离鉴定

深圳市某肉联厂屠宰的生猪现场检疫出的病猪样品中，经实验室检验分离出猪溶血性巴氏杆菌与非溶血性的G^-直杆菌（未知菌），它们对生猪能引起混合感染并有强的协同致病作用，混合感染病猪的心脏等病理变化与传统的猪巴氏杆菌病有所不同。     

戊型肝炎病毒感染对补体系统表达的影响

目的 探讨补体在戊型肝炎病毒(hepatitis E virus,HEV)感染孕妇及非孕妇患者中的表达水平.方法 采用免疫比浊法检测HEV感染孕妇及非孕妇患者血清中补体固有成分C3及C4水平;RT-qPCR法检测HEV感染孕妇及非孕妇患者全血中补体C3aR、CD55和CD59的表达水平.结果 HEV感染激活补体C3、C...     

The revealing power of a test case

‘Propagation, infection, and execution analysis’ (termed PIE) is used for predicting where faults can more easily hide in software. To make such predictions, programs are dynamically executed with test cases, and information concerning the test cases is collected into a histogram, each bin of which represents a single test case. The score in a bin predicts the likelihood that the test case will reveal a fault through the production of a failure (if a fault exists in the set of program locations that the test case executes). Preliminary experiments using program mutations suggest that the histogram technique presented in this paper can rank test cases according to their fault revealing ability.