Halos y lentes intraoculares multifocales: origen e interpretación

ObjectiveTo present the theoretical and experimental characterization of the halo in multifocal intraocular lenses (MIOL).MethodThe origin of the halo in a MIOL is the overlaying of 2 or more images. Using geometrical optics, it can be demonstrated that the diameter of each halo depends on the addition of the lens (ΔP), the base power (P^d), and the diameter of the IOL that contributes to the «non-focused» focus. In the image plane that corresponds to the distance focus, the halo diameter (δH^d) is given by: δH^d = d^pn ΔP/P^d, where d^pn is the diameter of the IOL that contributes to the near focus. Analogously, in the near image plane the halo diameter (δHⁿ) is: δHⁿ = d^pd ΔP/P^d, where d^pd is the diameter of the IOL that contributes to the distance focus. Patients perceive halos when they see bright objects over a relatively dark background. In vitro, the halo can be characterized by analyzing the intensity profile of the image of a pinhole that is focused by each of the foci of a MIOL.Results and conclusionsA comparison has been made between the halos induced by different MIOL of the same base power (20D) in an optical bench. As predicted by theory, the larger the addition of the MIOL, the larger the halo diameter. For large pupils and with MIOL with similar aspheric designs and addition (SN6AD3 vs ZMA00), the apodized MIOL has a smaller halo diameter than a non-apodized one in distance vision, while in near vision the size is very similar, but the relative intensity is higher in the apodized MIOL. When comparing lenses with the same diffractive design, but with different spherical-aspheric base design (SN60D3 vs SN6AD3), the halo in distance vision of the spherical MIOL is larger, while in near vision the spherical IOL induces a smaller halo, but with higher intensity due to the spherical aberration of the distance focus in the near image. In the case of a trifocal-diffractive IOL (AT LISA 839MP) the most noticeable characteristic is the double-halo formation due to the 2 non-focused powers.     

早期卧位踏车训练对下肢重度烧伤患者的效果

目的探讨早期卧位踏车训练在下肢重度烧伤患者功能康复中的临床效果。方法2016年10月至2017年12月,下肢重度烧伤患者30例分为对照组和观察组,各15例。对照组采用常规综合康复,观察组此基础上增加早期卧位踏车训练。入院时和住院治疗6周后,采用焦虑自评量表(SAS)、抑郁自评量表(SDS)、疼痛数字评分法(NRS)、Berg平衡量表(BBS)和6分钟步行测试进行评定。结果治疗后,两组SAS、SDS、NRS评分均明显降低(t>3.636,P<0.01),观察组低于对照组(t>2.319,P<0.05);观察组BBS评分和6分钟步行距离高于对照组(t>2.541,P<0.05)。结论早期卧位踏车训练对下肢重度烧伤患者功能恢复有一定促进作用。     

Phage Therapy in the Resistance Era: Where Do We Stand and Where Are We Going?

PurposeWidespread antibiotic-resistant bacteria are threatening the arsenal of existing antibiotics. Not only are antibiotics less likely to be effective today, but their extensive use continues to drive the emergence of multidrug-resistant pathogens. A new-old antibacterial strategy with bacteriophages (phages) is under development, namely, phage therapy. Phages are targeted bacterial viruses with multiple antibacterial effector functions, which can reduce multidrug-resistant infections within the human body. This review summarizes recent phage therapy clinical trials and patient cases and outlines the fundamentals behind phage treatment strategies under development, mainly through bench-to-bedside approaches. We discuss the challenges that remain in phage therapy and the role of phages when combined with antibiotic therapy.MethodsThis narrative review presents the current knowledge and latest findings regarding phage therapy. Relevant case reports and research articles available through the Scopus and PubMed databases are discussed.FindingsAlthough recent clinical data suggest the tolerability and, in some cases, efficacy of phage therapy, the clinical functionality still requires careful definition. The lack of well-controlled clinical trial data and complex regulatory frameworks have driven the most recent human data generation on a single-patient compassionate use basis. These cases often include the concomitant use of antibiotics, which makes it difficult to draw conclusions regarding the effectiveness of phages alone. However, human data support using antibiotics as phage potentiators and resistance breakers; thus, phage adjuvants are a promising avenue for near-term clinical development. Current knowledge gaps exist on the appropriate routes of administration, phage selection, frequency of administration, dosage, phage resistance, and pharmacokinetic and pharmacodynamic properties of the phages. In addition, we highlight that some phage therapies have mild adverse effects in patients.ImplicationsAlthough more translational research is needed before the clinical implementation is feasible, phage therapy may well be pivotal in safeguarding humans against antibiotic-resistant infections.     

水泵试验台液压夹紧装置设计

从系统机构设计、夹紧力分析、液压系统设计和电气控制原理等方面,阐述了水泵试验台液压夹紧装置的设计构造过程.为了保证试验时不发生泄漏现象,在管道联接端面采用抠槽密封处理技术,并对液压夹紧力进行计算与分析,得出在6.4 MPa的压力下,液压夹紧力约为88.238 kN,液压缸提供的最小工作压力为17.563 MPa.现场试验结果表明:与传统法兰联接方式相比,在规定试验压力下,该夹紧装置无泄漏现象,联接端面水力损失减小约0.156%,自动化程度高,水泵出厂检测台数增加约1.5倍,大幅度改善了水泵出厂检测的效率.     

Is the SAPS II score valid in surgical intensive care unit patients?

Aims and objectives We investigated the performance of the simplified acute physiology score II (SAPS II) in a large cohort of surgical intensive care unit (ICU) patients and tested the hypothesis that customization of the score would improve the uniformity of fit in subgroups of surgical ICU patients. Methods Retrospective analysis of prospectively collected data from all 12 938 patients admitted to a postoperative ICU between January 2004 and January 2009. Probabilities of hospital death were calculated for original and customized (C1‐SAPS II and C2‐SAPS II) scores. A priori subgroups were defined according to age, probability of death according to the SAPS II score, ICU length of stay (LOS), surgical procedures and type of admission. Results The median ICU LOS was 1 (1–3) day. ICU and hospital mortality rates were 5.8% and 10.3%, respectively. Discrimination of the SAPS II was moderate [area under receiver operating characteristic curve (aROC) = 0.76 (0.75–0.78)], but calibration was poor. This model markedly overestimated hospital mortality rates [standardized mortality rate: 0.35 (0.33–0.37)]. First‐level customization (C1‐SAPS II) did not improve discrimination in the whole cohort or the subgroups, but calibration improved in some subgroups. Second‐level customization (C2‐SAPS II) improved discrimination in the whole cohort [aROC = 0.82 (0.79–0.85)] and most of the subgroups (aROC range 0.65–86). Calibration in this model (C2‐SAPS II) improved in the whole cohort and in subgroups except in patients with ICU LOS 4–14 days and those undergoing neuro‐ or gastrointestinal surgery. Conclusions In this large cohort of surgical ICU patients, performance of the original SAPS II model was generally poor. Although second‐level customization improved discrimination and calibration in the whole cohort and most of the subgroups, it failed to simultaneously improve calibration in the subgroups stratified according to the type of surgery, age or ICU LOS.     

Investigation and Modelling of the Weight Wear of Friction Pads of a Railway Disc Brake

This paper presents the results of tests on the railway disc brake with regard to the weight wear of friction pads. The tests were carried out at a certified brake test bench where the friction-mechanical characteristics of the railway brake were determined. The test stand was additionally equipped with a thermal imaging camera to observe the contact between the brake pads and the brake disc. The scientific goal of the test is to evaluate the relationship between the weight wear of friction pads and the quantities characterizing the braking process. The quantities characterizing the braking process included pad-to-disc contact area, friction pad thickness, pad-to-disc pressure, and braking speed. A regression model to estimate the friction pad wear on the basis of a single braking with the given input quantities was determined. The greatest influence on the increase in weight wear of friction pads has the braking velocity, which was confirmed by the value of the correlation coefficient of the regression model at value 0.81. The pressure of the friction pad to the disc and the friction pad thickness do not have a significant effect on the weight wear described by the regression model, and the obtained correlation coefficient for these parameters was lower than the value of 0.2.     

Wear Performance of Circular Shim against Cam in Engine Bench Test

Unlike the conventional engine, the valve train of a certain type of engine uses a circular shim instead of a tappet to wear against the cam. To verify the reliability of the shim, an engine bench test was used to test its wear performance. The total duration of the bench test was 1000 h, which was divided into three stages. In each stage, the test equipment was stopped, and the shims were disassembled to observe the surface morphology during the worn process. Precious long-term data were obtained. With the extension of the bench test time, weight loss increased. The maximum weight loss occurs 1000 h after worn, which is about twice that of 350 h. During the wear process, a plastic flow of material was found on the subsurface, and fatigue wear marks occurred on the surface. With an increase in test time, the wear marks increased, leading to material spalling and the formation of pits. The wear mechanism was the mixed wear of fatigue wear and adhesive wear.