Natural ventilation for reducing airborne infection in hospitals

High ventilation rate is shown to be effective for reducing cross-infection risk of airborne diseases in hospitals and isolation rooms. Natural ventilation can deliver much higher ventilation rate than mechanical ventilation in an energy-efficient manner. This paper reports a field measurement of naturally ventilated hospital wards in Hong Kong and presents a possibility of using natural ventilation for infection control in hospital wards. Our measurements showed that natural ventilation could achieve high ventilation rates especially when both the windows and the doors were open in a ward. The highest ventilation rate recorded in our study was 69.0 ACH. The airflow pattern and the airflow direction were found to be unstable in some measurements with large openings. Mechanical fans were installed in a ward window to create a negative pressure difference. Measurements showed that the negative pressure difference was negligible with large openings but the overall airflow was controlled in the expected direction. When all the openings were closed and the exhaust fans were turned on, a reasonable negative pressure was created although the air temperature was uncontrolled.     

Droplet fate in indoor environments,or can we prevent the spread of infection?

Abstract Abstract When considering how people are infected and what can be done to prevent the infections, answers from many disciplines are sought: microbiology, epidemiology, medicine, engineering, and physics. There are many pathways to infection spread, and among the most significant from the epidemiological point of view is airborne transport. Microorganisms can become airborne when droplets are generated during speech, coughing, sneezing, vomiting, or atomization of feces during sewage removal. The fate of the droplets is governed by the physical principles of transport, with droplet size being the most important factor affecting their dispersion, deposition on surfaces and determining the survival of microorganisms within the droplets. In addition, physical characteristics of the indoor environment as well as the design and operation of building ventilation systems are of critical importance. Do we understand the mechanisms of infection spread and can we quantify the droplet dynamics under various indoor conditions? Unfortunately no, as this aspect of infection spread has attracted surprisingly little scientific interest. However, investigations of numerous cases in which a large number of people were infected show how critical the physics of microorganism spread can be. This paper reviews the state of knowledge regarding mechanisms of droplet spread and solutions available to minimize the spread and prevent infections.     

Eggcrate UV: a whole ceiling upper‐room ultraviolet germicidal irradiation system for air disinfection in occupied rooms

A novel whole ceiling upper‐room ultraviolet germicidal irradiation (UVGI) system [eggcrate ultraviolet (UV)] has been developed that incorporates open‐cell ‘eggcrate’‐suspended ceiling panels and bare UV lamps with a ceiling fan. Upper‐room UVGI is more effective for air disinfection than mechanical ventilation at much lower installation and operating costs. Conventional upper‐room UVGI fixtures employ multiple tightly spaced horizontal louvers to confine UV to the upper‐room. These louvered fixtures protect occupants in the lower‐room from UV‐induced eye and skin irritation, but at a major cost to fixture efficiency. Using a lamp and ballast from a conventional upper‐room UVGI fixture in the eggcrate UV system, the germicidal efficacy was markedly improved even though the UV radiation emitted by the lamp was unchanged. This fundamental change in the application of upper‐room UVGI air disinfection should permit wider, more effective application of UVGI globally to reduce the spread of airborne infection.     

井间非均质渗透率分形预测

储集层渗透率空间分布既有严重的非均质性，又有统计自相似性。在预测泌阳凹陷双河油田４３７断块Ⅱ油组１小层井间渗透率非均质性时，首先根据取心井岩心实测渗透率与测井资料间的关系，建立渗透率解释模型；用该模型解释单井测井资料，得到逐点渗透率预测值，等序处理构成非均质渗透率序列，并研究豪斯特指数；根据井斜资料将井深校正为海拔高程，建立井间预测网格；用分形克里格法预测井间每个网格结点渗透率，用变序技术处理层状非均质分布问题，用权门槛技术解决泥质夹层预测问题，得到井间预测剖面；用取心井已知渗透率对预测结果进行交叉检验，计算单层平均预测误差（通过５口井资料的交叉检验，单层预测的平均误差为３５．１％）。将此预测结果用于该断块４６２注采井组分析，总结出７种储集层过渡类型，评价井组的单层连通情况，预测油水分布动态。预测成果还可用于识别厚油层内的夹层。图２表１参５（郭海莉摘）     

院内感染系统中的数据预处理

在医院中院内感染是一个不可忽视的问题。医院内每天产生大量的数据,迫切需要挖掘出这些数据中与院内感染有关的因素。而数据预处理技术的好坏直接影响到数据挖掘的结果。介绍了针对院内感染数据挖掘系统,在关联规则挖掘前的数据预处理技术。     

人巨细胞病毒感染诱导U251星形胶质瘤细胞凋亡及其差异蛋白的表达

目的分析人巨细胞病毒(HCMV)感染对人星形胶质瘤细胞凋亡的影响及其细胞内差异蛋白的表达。方法以HCMV AD169株感染U251细胞,复制HCMV体外感染模型,通过RT-PCR和免疫细胞化学技术检测HCMV IE蛋白和结构蛋白pp65的表达。用AnnexinⅤ-FITC和PI染色检测细胞凋亡,通过SELDI-TOF质谱分析感染细胞内差异蛋白的表达。结果HCMV感染后6 h,U251细胞经RT-PCR可扩增出242 bp的IE基因条带,感染后3 d,细胞核内有大量IE蛋白表达,核周及细胞浆内有大量pp65蛋白表达。病毒感染后3 d,约47%的细胞产生凋亡。HCMV感染后细胞内Caspase-8和磷脂酶A2的表达明显增加。结论HCMV感染可能通过上调Caspase-8和磷脂酶A2的表达而诱导U251星形胶质瘤细胞产生凋亡损伤。     

婴幼儿先天性巨细胞病毒感染性感觉神经性耳聋的研究进展

先天性巨细胞病毒感染是引起婴幼儿感觉神经性耳聋的重要原因,也是先天性巨细胞病毒感染最常见的后遗症。耳聋的症状可在新生儿期出现,也可在出生后一段时间(通常在1岁左右)出现。对患儿使用安全范围内的抗病毒药物治疗可以改善听力。本文就婴幼儿先天性巨细胞病毒感染性感觉神经性耳聋的研究进展作一综述。     

烟草灰霉病侵染条件的研究

烟草灰霉病是黑龙江烟区新发现病害，个别地块已造成严重损失。自１９９０～１９９５年利用田间试验和控制条件接种方法，研究了烟草灰霉病病菌侵染来源和侵染规律，试验发现：①灰霉病菌Ｂｏｔｒｙｔｉｓｃｉｎｅｒｅａ侵染烟株的最适宜温度在１８℃左右，９℃以下或２７℃以上不能发生侵染，该菌发生侵染还必须满足９ｈ以上的湿润时间，１２～２４ｈ持续湿润利于侵染，光照对病菌侵染有抑制作用。②病菌的侵染来源主要是来自烟株病残体产生的分生孢子。③黑龙江烟区有两个侵染高峰，一个在６月中、下旬，另一个在８月中、下旬。这期间低温、多雨侵染率较高。     

BCLA CLEAR - Contact lens complications

Contact lens-related complications are common, affecting around one third of wearers, although most are mild and easily managed. Contact lenses have well-defined anatomical and physiological effects on the ocular surface and can result in other consequences due to the presence of a biologically active material. A contact lens interacts with the tear film, ocular surface, skin, endogenous and environmental microorganisms, components of care solutions and other antigens which may result in disease specific to contact lens wear, such as metabolic or hypersensitivity disorders. Contact lens wear may also modify the epidemiology or pathophysiology of recognised conditions, such as papillary conjunctivitis or microbial keratitis. Wearers may also present with intercurrent disease, meaning concomitant or pre-existing conditions unrelated to contact lens wear, such as allergic eye disease or blepharitis, which may complicate the diagnosis and management of contact lens-related disease.Complications can be grouped into corneal infection (microbial keratitis), corneal inflammation (sterile keratitis), metabolic conditions (epithelial: microcysts, vacuoles, bullae, tight lens syndrome, epithelial oedema; stromal: superficial and deep neovascularisation, stromal oedema [striae/folds], endothelial: blebs, polymegethism/ pleomorphism), mechanical (corneal abrasion, corneal erosion, lens binding, warpage/refractive error changes; superior epithelial arcuate lesion, mucin balls, conjunctival epithelial flaps, ptosis, discomfort), toxic and allergic disorders (papillary conjunctivitis, solution-induced corneal staining, incomplete neutralisation of peroxide, Limbal Stem Cell Deficiency), tear resurfacing disorders/dry eye (contact lens-induced dry eye, Meibomian gland dysfunction, lid wiper epitheliopathy, lid parallel conjunctival folds, inferior closure stain, 3 and 9 o'clock stain, dellen, dimple veil) or contact lens discomfort. This report summarises the best available evidence for the classification, epidemiology, pathophysiology, management and prevention of contact lens-related complications in addition to presenting strategies for optimising contact lens wear.     

医院获得性血流感染的6种常见病原菌耐药性及患者死亡情况分析

目的研究医院获得性血流感染的6种主要病原菌耐药情况以及血流感染后患者死亡情况。方法对由大肠埃希菌、金黄色葡萄球菌、铜绿假单胞菌、鲍曼不动杆菌、屎肠球菌、粪肠球菌所致的492例医院获得性血流感染病例及死亡情况进行回顾性分析。结果大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌、鲍曼不动杆菌、屎肠球菌、粪肠球菌所致医院获得性血流感染患者总体死亡率分别为22.29%、23.44%、28.28%、28.30%、36.25%、38.46%。血流感染大肠埃希菌中产超广谱β-内酰胺酶菌株占50.96%,金黄色葡萄球菌中耐甲氧西林金黄色葡萄球菌占62.63%,多耐药菌株占所有铜绿假单胞菌的23.44%,耐碳青霉烯菌株占所有鲍曼不动杆菌的54.72%,耐高单位庆大霉素菌株在屎肠球菌和粪肠球菌中分别占71.25%和56.41%。结论粪肠球菌所致医院获得性血流感染的患者死亡率最高,耐甲氧西林金黄色葡萄球菌所致死亡率高于甲氧西林敏感金黄色葡萄球菌,耐碳青霉烯鲍曼不动杆菌所致死亡率高于非耐药者。