A simplified approach to radionuclide venography: concise communication

A simplified method has been developed for performing radionuclide venography. The method makes use of the scintillation camera and a synchronized whole-body scanning bed. This technique permits a more integrated presentation of the data and is performed in conjunction with a standard ventilation-perfusion lung study. The total amount of 99mTc tracer injected is 2 mCi.     

An algorithm for regular and irregular Coulomb and Bessel functions of real order to machine accuracy

We describe an algorithm to evaluate a wide class of functions and their derivatives, to extreme precision (25–30S) if required, which does not use any function calls other than square root. The functions are the Coulomb functions of positive argument (F_λ(x, η), G_λ(x, η), x > 0, η, λ real) and hence, as special cases with η = 0, the cylindrical Bessel functions (J_μ(x), Y_μ(x), x > 0, μ real), the spherical Bessel functions (i_λ(x), y_λ(x), x > 0, λ real), Airy functions of negative argument Ai(-x), Bi(-x) and others. The present method has a number of attractive features: both the regular and irregular solution are calculated, all others of the functions can be produced from a specified minimum (not necessarily zero) to a specified maximum, functions of a single order can be found without all of the orders from zero, the derivatives of the functions arise naturally in the solution and are readily available, the results are available to different precisions from the same subroutine (in contrast to rational approximation techniques) and the methods can be used for estimating final accuracies. In addition, the sole constant required in the algorithm is π, no precalculated arrays of coefficients are needed, and the final accuracy is not dependent on that of other subroutines. The method works most efficiently in the region x ≈ 0.5 to x ≈ 1000 but outside this region the results are still reliable, even though the number of iterations within the subroutine rises. Even in these more asymptotic regions the unchanged algorithm can be used with known accuracy to test other specific subroutines more appropriate to these regions. The algorithm uses the recursion relations satisfied by the Coulomb functions and contains a significant advance over Miller's method for evaluating the ratio of successive minimal solutions (F_λ+1/F_λ). It relies on the evaluation of two continued fractions and no infinite series is required for normalisation: instead the Wronskian is used.     

What is learned in note taking?

Two experiments with 130 undergraduates investigated the effects of note taking and reviewing on learning from text. Findings support the encoding function of note taking and demonstrate that unguided elaboration hindered performance on teacher-made tests. When delayed tests were based on S's own notes, average scores were nearly twice as high as when test were based on either teacher selection of test material or on other Ss' notes (for all reviewing treatments). Interpretations are in terms of metacognitions related to taking notes, transfer-appropriate processing, and the requirements necessary for elaboration to be an effective learning strategy. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The design of an inter-task communication scheme

The paper describes an implemented inter-task communication scheme, and its design motivation. The scheme provides a well-defined environment for all situations, including abnormal ones, such as misuse of its facilities. The main design goal is that users of the scheme should be able to verify their communication logic by inspection. Methods are described for reducing the complexity of communication logic to a minimum. The analogy with inter-CPU communication is discussed.     

先进的企业级性能催化下一代SAS系统

引言当存储器OEM和集成厂商在引进并采用基于SAS的系统时,都会希望能够提供流量管理和安全领域所需的光纤通道及企业级特性。为满足这些需求,在即将推出的SAS 2.0规范中引入了端对端分区的概念。根据定义,SAS协议在指定的域中支持最多16384个设备(启动器、目标器、扩展器和/或虚拟设备),然而,在实际应用中,     

Association between cigarette smoking and C-reactive protein in a representative, population-based sample of adolescents.

Although related to inflammatory markers in adults, little is known about the association between cigarette smoking and C-reactive protein (CRP) in adolescent smokers. We examined the association between high-sensitivity CRP (hs-CRP) concentrations and smoking in youth. We used data from a cross-sectional, province-wide survey of a representative sample of youth conducted in Quebec, Canada, in 1999. Data were collected in self-report questionnaires completed by participants and their parents. Participants provided a fasting blood sample, and anthropometric measures were undertaken by trained technicians. The present analysis pertains to 1,501 adolescents aged 13 and 16 years who completed questionnaires and for whom blood samples were available. The independent association between a six-category indicator of smoking status and elevated hs-CRP, defined as a value at least in the 90th percentile of the age- and sex-specific CRP distribution, was assessed in multiple logistic regression analyses controlling for potential confounders. Relative to never-smokers, the odds ratios (95% confidence intervals) for puffers (i.e., never smoked a whole cigarette), those who smoked but not in the past month, light past-month smokers, moderate past-month smokers, and heavy past-month smokers were 1.04 (0.55-1.98), 1.76 (1.06-2.94), 1.39 (0.70-2.76), 2.07 (0.96-4.42), and 2.40 (1.18-4.88), respectively. Our data suggest a positive association between smoking status and elevated CRP in adolescents, and in particular among heavier past-month smokers. Damage related to cigarette smoking may begin soon after tobacco use initiation, reinforcing the preventive message that no level of smoking is safe in youth.     

Compact spectrum splitting photovoltaic module with high efficiency

We have designed, fabricated, and tested a small, integrated photovoltaic module comprised of two separately‐contacted, high efficiency, multijunction solar cells and non‐imaging optics that both concentrate and spectrally split the incoming light. This hybrid design allows us to individually optimize the tandem cells and optical elements. The system has a measured module efficiency, including optical and packaging losses but not power combination losses, of 38.5 ± 1.9% under the AM1.5 direct terrestrial spectrum. The internal optics concentrate the light by a factor of approximately 20. We find excellent agreement between the modeled and measured performance. This is the highest confirmed conversion efficiency demonstrated for a photovoltaic module. Copyright © 2010 John Wiley & Sons, Ltd.     

Insight from in situ microscopy into which precipitate morphology can enable high strength in magnesium alloys

Magnesium alloys, while boasting light weight, suffer from a major drawback in their relatively low strength. Identifying the microstructural features that are most effective in strengthening is therefore a pressing challenge. Deformation twinning often mediates plastic yielding in magnesium alloys. Unfortunately, due to the complexity involved in the twinning mechanism and twin-precipitate interactions, the optimal precipitate morphology that can best impede twinning has yet to be singled out. Based on the understanding of twinning mechanism in magnesium alloys, here we propose that the lamellar precipitates or the network of plate-shaped precipitates are most effective in suppressing deformation twinning. This has been verified through quantitative in situ tests inside a transmission electron microscope on a series of magnesium alloys containing precipitates with different morphology. The insight gained is expected to have general implications for strengthening strategies and alloy design.