Effect of an intervening screen on accommodation to a distant object

Background : An intervening screen has been suggested to induce an inward shift of accommodation when viewing a distant object. This is an example of the Mandelbaum effect. However, there have been no objective measures of the magnitude of this effect in this particular situation. Methods : Accommodation was recorded with an infra-red optometer, while subjects (n = 16) viewed a distant letter target with or without an intervening screen. Screens were placed near the individual dark focus distance or at 50 cm. In a second experiment the contrast of the distant target was varied and subjects (n = 5) viewed the target directly or through a screen placed near the individual dark focus distance. Results : In the main experiment, the Mandelbaum effect was not significantly different from zero and was less than 0.5 D in every subject. In addition, accommodation was not more variable when viewing through the screen. However, it may be that some subjects do demonstrate a Mandelbaum effect while others do not. The individual dark focus level did not predict susceptibility to the Mandelbaum effect for a screen at the dark focus. Subjects reported their perceptions of the tasks and some noted changes in the perceived distances of objects when viewing through a screen. In the second experiment, the Mandelbaum effect (< 0.6 D) did not vary with distant target contrast.     

The Influence of Liquid Crystalline Phases on Drug Percutaneous Absorption. II. Permeation Studies Through Excised Human Skin

The influence of liquid crystalline (LC) phases on the percutaneous absorption of a model compound (ploxicromil; PXC) was studied with the use of the phase diagram for the surfactant, oil, and water comprising the vehicles. Two separate sets of vehicles, representing two different tie lines lying in the Ll + LC phase region, were prepared in which the concentration of LC was varied over the range 0 to 100% along each tie line. In vitro permeation studies of PXC from these systems were conducted using excised human skin and the flux values determined as a function of the percentage LC present in the vehicles. In virtually all cases, the flux reached a peak at 5-10% LC and then decreased significantly as the fraction of LC present increased further. The pattern of behavior observed is discussed in terms of current theories describing membrane-controlled and vehicle-controlled diffusion, none of which adequately model the results obtained.     

The influence of sample dimensions on hydroxyl ion release from calcium hydroxide products

Abstract – The purpose of this study was to compare the rate of hydroxyl ion release from commercially available setting and non-setting calcium hydroxide products. The rate of hydroxyl ion release is important, as this has been suggested to be the main factor in the therapeutic activity of these products. In total, hydroxyl ion release was measured from 1104 samples of Dycal, Life, Calasept and Hypocal in solution using in vitro titration. The rate of hydroxyl ion release was measured for up to 14 days, using two sizes of sample surface area. The dimensions of the exposed sample surface area was found to be an important physical constraint to the hydroxyl ion release from non-setting calcium hydroxide products, whereas this was not found to be the case with setting products. The range in hydroxide activity between products was found to be 298%. In rank order of hydroxide ion release, from the most to the least active was: Hypocal, Calasept, Life and Dycal. The differences in the rate of hydroxyl ion release from these products may have some implications for their clinical applications. It is suggested that in cases where the oral healing responses have been poorer than expected, the size and seal of prepared cavities could have negatively influenced the therapeutic release of hydroxyl ions from non-setting calcium hydroxide products.     

Periodic Optimal Hypersonic Scramjet Cruise

Fuel-optimal periodic cruise paths are determined numerically for a hypersonic vehicle with more realistic aerodynamic and scramjet engine models than used in previous work. A modification of the shooting method, called the minimizing-boundary-condition method, is used to increase the region of convergence of the solution to the two-point boundary-value problem required to satisfy the first-order necessary conditions. The resulting extremal trajectories are shown to be locally minimizing by a second-order sufficiency condition. Little fuel improvement is obtained over the full-throttle steady-state cruise if the model with an engine-off-drag penalty is used. However, altitude changes of over 25 per cent from its lowest value on the periodic path are obtained. If the model without engine-off-drag penalty is used, the fuel improvement for the optimal periodic cruise is 5 per cent over the full-throttle steady-state cruise.     

ATVs: motorized toys or vehicles for children?

OBJECTIVES: To compare the nature of injuries from all-terrain vehicles (ATVs) to those from bicycling, dirtbikes/motocross, and motor vehicle crashes. DESIGN: Data on injuries from the mechanisms outlined above were obtained through CHIRPP (the Canadian Hospitals Injury Reporting and Prevention Program) and hospital records. SETTING: A Canadian tertiary pediatric center. SUBJECTS: Cases presenting to the emergency department over a 10 year period. MAIN OUTCOME MEASURES: Comparison between demographics, mechanisms and natures of injuries sustained, disposition from the emergency department, and lengths of hospital stay. RESULTS: Contrary to bicycling, ATV related injuries occurred among older ages and appeared to result less often from loss of control. Severe injuries resulting in deep soft tissue trauma and fracture/dislocations were 1.7 and 1.5 times, respectively, more frequent among ATV trauma than bicycling (p<0.01). In addition, ATV related injuries were located more frequently in the trunkal, hip, lower extremity, and spinal regions. Conversely, ATV related trauma bore significant similarities regarding body part and nature of the injury to both motor vehicle crash (MVC) and dirtbike related injuries. Akin to dirtbike and MVC related trauma, ATV related injuries more frequently required admission to the ward or intensive care unit compared to bicycling injuries (30.8% v 9.6%, p<0.0001), and used a proportionally larger amount of hospital resources with respect to overall in-hospital and intensive care unit days. CONCLUSIONS: Although ATVs may be considered recreational for children, their associated injury patterns, severity, and costs to the healthcare system more closely resemble those from motorized vehicles and are more significant than bicycling. Strict policy to reflect this must be developed and acknowledged by the public, industry, and legislative bodies.     

远程医疗系统车载化应用及发展趋势

远程医疗是当今世界最重要、发展最快的两大领域医学和通信技术的结合。回顾远程医疗系统及其车载化应用的发展概况,重点介绍车载化系统的构成,详细介绍车载化系统研制过程中解决的一些关键技术问题,并对远程医疗系统车载化应用的发展进行展望。     

Seatbelt use,attitudes, and changes in legislation: an international study

BACKGROUND: The use of seat belts is among the most effective methods of reducing injury in motor vehicle crashes. We examined trends in seat belt use by university students from 13 European countries between 1990 and 2000, in relation to changes in legislation, attitudes, and hazardous driver behaviors. METHODS: Data were collected via an anonymous standardized questionnaire from university students in Belgium, England, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, the Netherlands, Poland, Portugal, and Spain. There were 10,576 respondents in 1990, and 10,294 in 2000. Data were also collected from 1672 students in the United States in 2000. Analyses were performed in early 2002. RESULTS: Reported seat belt use increased from 63% to 73% in male students, and from 66% to 77% in female students over the decade. There were marked increases in seat belt use in countries with changes in legislation or enforcement from 1990 to 2000, with 24% to 64% more respondents reporting seat belt use in 2000. The prevalence of use and noted changes during this period correlated with findings from national surveys (r= 0.91). Attitudes to seat belt use were associated with behavior both within and between countries. Nonuse of seat belts was positively related to alcohol-impaired driving and failure to obey speed limits. CONCLUSIONS: Legislation has a substantial impact on the use of vehicle seat belts, but additional gains require efforts to change attitudes within the university student population.     

客车坠江事故的现场救援体会

目的探讨客车坠江事故的特点和现场救援措施,以提高救援水平。方法对3起客车坠江事故的伤害特点及救援措施进行回顾性分析。结果3起客车坠江事故均发生在夜晚,均由司机人为因素引起,经现场快速评估和反应、及时营救落水人员、迅速分类救治及安全转运岸上伤员,108名乘客中死亡66名,存活42名。幸存者均为从卧铺大客车车窗甩出的乘客。结论客车坠江事故具有不可预见性,时间、地点不确定性和伤亡突然性、大量性的特点,需武警、消防、海事及医疗等部门的分工协作。减灾措施要着手解决夜间照明、运输工具及工程抢险救援问题。建议建立水上应急救护队,客车装配救生设备。     

Protein and Peptide Drug Delivery: Oral Approaches

Till recent, injections remained the most common means for administering therapeutic proteins and peptides because of their poor oral bioavailability. However, oral route would be preferred to any other route because of its high levels of patient acceptance and long term compliance, which increases the therapeutic value of the drug. Designing and formulating a polypeptide drug delivery through the gastro intestinal tract has been a persistent challenge because of their unfavorable physicochemical properties, which includes enzymatic degradation, poor membrane permeability and large molecular size. The main challenge is to improve the oral bioavailability from less than 1% to at least 30-50%. Consequently, efforts have intensified over the past few decades, where every oral dosage form used for the conventional small molecule drugs has been used to explore oral protein and peptide delivery. Various strategies currently under investigation include chemical modification, formulation vehicles and use of enzyme inhibitors, absorption enhancers and mucoadhesive polymers. This review summarizes different pharmaceutical approaches which overcome various physiological barriers that help to improve oral bioavailability that ultimately achieve formulation goals for oral delivery.