Conventional consent with opting in versus simplified consent with opting out: an exploratory trial for studies that do not increase patient risk

PURPOSE: This study aimed to analyze the results of laser in situ keratomileusis (LASIK) in different degrees of myopia. MATERIAL AND METHODS: Three hundred consecutive eyes were divided into 4 groups according to their degree of preoperative myopia. Group I was between -3 and -6 diopters (D) (28 eyes), low myopia. Group II was between -6.25 and -10 D (138 eyes), moderate myopia. Group III was between -10.25 and -15 D (91 eyes), high myopia. Group IV was between -15.25 and -25.50 D (43 eyes), extremely high myopia. Patients were observed for 6 to 25 months. RESULTS: For group I, the preoperative spherical equivalent was -5.12 D +/- 0.81 standard deviation (SD), corrected visual acuity was 0.88 +/- 0.14 (SD), and keratometry was 44.09 D +/- 1.65 (SD). At the last check-up, the spherical equivalent was -0.42 D +/- 0.98 (SD), corrected visual acuity was 0.89 +/- 0.15 (SD), keratometry was 39.11 D +/- 1.61 (SD). For group II, preoperative spherical equivalent was -8.33 D +/- 1.24 (SD), corrected visual acuity was 0.72 +/- 0.22 (SD), keratometry was 44.34 D +/- 1.64 (SD). At last check-up, the spherical equivalent was -0.19 D +/- 1.22 (SD), corrected visual acuity was 0.76 +/- 0.17 (SD), keratometry was 37.56 D +/- 1.90 (SD). For group III, the preoperative spherical equivalent was -12.37 D +/- 1.49 (SD), corrected visual acuity was 0.58 +/- 0.23 (SD), and keratometry was 44.06 D +/- 1.63 (SD). At last check-up, spherical equivalent was -0.55 D +/- 1.63 (SD), corrected visual acuity was 0.61 +/- 0.18 (SD), and keratometry was 35.88 D +/- 2.18 (SD). For group IV, the preoperative spherical equivalent was -19.04 +/- 2.82 (SD), corrected visual acuity was 0.37 +/- 0.17 (SD), and keratometry was 44.02 D +/- 1.30 (SD). At last check-up, spherical equivalent was -1.49 D +/- 1.54 (SD), corrected visual acuity was 0.44 +/- 0.18 (SD), and keratometry was 33.94 D +/- 2.54 (SD). CONCLUSION: With some exceptions, LASIK results generally are acceptable and stable. Nevertheless, the scatter of some cases shows that there is room for improvement, even in the most sophisticated excimer software. The high regression of group I proves the need to sample multizone software to determine whether stability is improved. Although visual results are better in patients with lower myopia, the patients whose eyes had higher ametropia more often showed improvement in their visual acuity. This may be because of the greater postoperative size of the image on the macula.     

Zirconium diboride nanofiber generation via microwave arc heating

Ultrahigh temperature zirconium diboride nanofibers were produced by microwave arc heating using micron-sized raw powder. While microwave heating the ZrB(2) powder, the development of local arcing led to rapid heating and solidification of the samples, along with the creation of nanofibers. The morphology of these high aspect ratio nanofibers was characterized using scanning electron microscopy and transmission electron microscopy. Energy dispersive x-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction showed the composition to contain zirconium, boron, nitrogen, aluminum and oxygen as well as the crystallographic orientation. ZrB(2) nanofiber applications include aerospace and other harsh environments.     

Vortex beam propagation through atmospheric turbulence and topological charge conservation

The propagation of vortex beams through weak-to-strong atmospheric turbulence is simulated and analyzed. It is demonstrated that the topological charge of such a beam is a robust quantity that could be used as an information carrier in optical communications. The advantages and limitations of such an approach are discussed.     

<Emphasis Type="Italic">In Situ</Emphasis> Local Measurement of Austenite Mechanical Stability and Transformation Behavior in Third-Generation Advanced High-Strength Steels

Austenite mechanical stability, i.e., retained austenite volume fraction (RAVF) variation with strain, and transformation behavior were investigated for two third-generation advanced high-strength steels (3GAHSS) under quasi-static uniaxial tension: a 1200 grade, two-phase medium Mn (10 wt pct) TRIP steel, and a 980 grade, three-phase TRIP steel produced with a quenching and partitioning heat treatment. The medium Mn (10 wt pct) TRIP steel deforms inhomogeneously via propagative instabilities (Lüders and Portevin Le Châtelier-like bands), while the 980 grade TRIP steel deforms homogenously up to necking. The dramatically different deformation behaviors of these steels required the development of a new in situ experimental technique that couples volumetric synchrotron X-ray diffraction measurement of RAVF with surface strain measurement using stereo digital image correlation over the beam impingement area. Measurement results with the new technique are compared to those from a more conventional approach wherein strains are measured over the entire gage region, while RAVF measurement is the same as that in the new technique. A determination is made as to the appropriateness of the different measurement techniques in measuring the transformation behaviors for steels with homogeneous and inhomogeneous deformation behaviors. Extension of the new in situ technique to the measurement of austenite transformation under different deformation modes and to higher strain rates is discussed.     

Determination of lead in wine and rum samples by flow injection-hydride generation-atomic absorption spectrometry

A method for direct determination of lead in wine and rum samples was developed, using a flow injection hydride generation system coupled to an atomic absorption spectrometer with flame-quartz atomizer (FI-HG-AAS). Lead hyride (PbH(4)) was generated using potassium ferricyanide (K(3)Fe(CN)(6)), as oxidant and sodium tetrahydroborate (NaBH(4)) as reductant. Samples were acidified to 0.40% (v/v) HCl for wine and to 0.30% (v/v) HCl for rum, which were then mixed on-line with 3% (m/v) K(3)Fe(CN)(6) solution in 0.03% (v/v) HCl prior to reaction with 0.2% (m/v) alkaline NaBH(4) solution. Lead contents of a rum and two different red wine samples were determined by FI-HG-AAS agreed with those obtained by ICP-MS. The analytical figures of merit of method developed were determined. The calibration curve was linear up to 8.0 microg L(-1) Pb with a regression coefficient of 0.998. The relative error was lower than 4.58%. The relative standard deviation (n=7) was better than 12%. A detection limit of 0.16 microg L(-1) was achieved for a sample volume of 170 microL.     

Parental involvement in middle school: A meta-analytic assessment of the strategies that promote achievement.

Early adolescence is often marked by changes in school context, family relationships, and developmental processes. In the context of these changes, academic performance often declines, while at the same time the long-term implications of academic performance increase. In promoting achievement across elementary and secondary school levels, the significant role of families, family–school relations, and parental involvement in education has been highlighted. Although there is a growing body of literature focusing on parental involvement in education during middle school, this research has not been systematically examined to determine which types of involvement have the strongest relation with achievement. The authors conducted a meta-analysis on the existing research on parental involvement in middle school to determine whether and which types of parental involvement are related to achievement. Across 50 studies, parental involvement was positively associated with achievement, with the exception of parental help with homework. Involvement that reflected academic socialization had the strongest positive association with achievement. Based on the known characteristics of the developmental stage and tasks of adolescence, strategies reflecting academic socialization are most consistent with the developmental stage of early adolescence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

奥斯龙机械公司新一代低固形物TM连蒸系统 在Willamette的Hawesville,Kentucky纸厂试车成功

介绍了采用低固形物蒸煮对蒸煮运转性能的影响。总结了该蒸煮方法的研究开发、工作原理和实际应用中应注意的事项;集中讨论了低固形物蒸煮的最新成果。重点总结了Ｋｅｎｔｕｃｋｙ纸厂１９９７年３月投入运营的首台用于低固形物蒸煮的单管液相蒸煮系统的成功经验     

The influence of precision requirements and cognitive challenges on upper extremity joint reaction forces,moments and muscle force estimates during prolonged repetitive lifting

Prolonged repetitive lifting is a whole-body exertion. Despite this, the roles and physical exposures of the upper extremities are frequently neglected. The influence of precision requirements and cognitive distractions on upper extremity responses when lifting was evaluated by quantifying several biomechanical upper extremity quantities. Nine participants completed four 30-min lifting tasks with and without simultaneous cognitive distractions and/or precision placement constraints. Specific metrics evaluated were joint reaction forces and moments (wrist, elbow and shoulder) and modelled shoulder muscle forces (38 defined shoulder muscle mechanical elements). The addition of a precision requirement increased several metrics by up to 43%, while the addition of the cognitive distraction task had minimal influence. Furthermore, several metrics decreased by up to 14% after the first 10 min of lifting, suggesting a temporal change of lifting strategy.