Developing better critical paths in healthcare: combining 'best practice' and the quantitative approach

Critical paths are tools to manage healthcare delivery and ensure favorable patient outcomes. Unfortunately, many of these paths are not evaluated or revised after their initial development. One potential problem faced by nursing managers is that critical paths may lose relevance in a rapidly changing healthcare environment. The authors suggest one strategy to strengthen existing critical paths in a way that is responsive to these changes.     

Diffusion Path Theorems for Ternary Diffusion Couples

A review is given of 17 theorems concerning diffusion paths in ternary diffusion couples published by Kirkaldy and Brown in 1963. An additional 11 theorems are given herein that were taken from work published on diffusion paths after that time. The new theorems are concerned primarily with diffusion paths that result from crossing multiple-phase regions in an interdiffusion zone. The theorems describe a method for classifying microstructural boundaries between the regions and a catalog of diffusion path features that are unique to each type of boundary. In addition, a proposal is given for how to plot diffusion paths in quaternary and higher order systems.     

Stress Paths in Relation to Deep Excavations

The mechanical behavior of many soils such as stiff clays depends on their current effective-stress states and stress history. For improving design and analysis of soil-structure interaction associated with deep excavations in these soils, it is important to understand effective-stress changes around excavations caused by both horizontal and vertical stress relief. In this paper, total and effective-stress variations adjacent to a diaphragm wall during construction of a 10-m-deep excavation in stiff fissured clay are reported and discussed. Interpreted field stress paths are compared with some relevant laboratory triaxial stress path tests, which simulate the horizontal and vertical stress relief in the field at an appropriate stress level. The interpreted field effective-stress paths in front of the wall are found to be similar to laboratory stress paths determined in undrained extension tests. Field stress paths behind the wall do not correspond particularly well with those from laboratory undrained compression tests, except when the stress state approaches active failure. The conventional undrained assumption does not seem to hold for the soil located immediately behind the wall during a relatively rapid excavation in the stiff clay.     

Configural processing in the perception of apparent biological motion.

In classic demonstrations of apparent motion, observers typically report seeing motion along the shortest possible path between 2 sequentially presented objects. However, when realistic photographs of a human body are sequentially presented at slow temporal rates, observers report paths of apparent motion that arc consistent with the movement limitations of the human body even when those paths are not the shortest possible. The current set of experiments examined those aspects of the human form that lead to the perception of biomechanically consistent paths of motion. The authors' findings suggest that the perception of apparent biological motion extends to human movements that involve inanimate objects. The authors also report that observers can perceive apparent motion of nonbiological objects in a manner similar to apparent motion of human bodies. However, a global hierarchy of orientation and position cues resembling the human form is required for the perception of these paths. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

硫含量对超高强度钢塑性的影响

不同硫含量的两种超高强度钢,其拉伸强度和断后伸长率基本相当,而断面收缩率相差较大。利用定量金相、扫描电镜和能谱分析等方法,研究了夹杂物对拉伸行为的影响。结果表明断面收缩率与夹杂物平均自由程密切相关。夹杂物平均自由程较小的钢中微孔洞以内颈缩的方式连接,裂纹较容易形成与扩展,导致断面收缩率降低。而夹杂物平均自由程较大的钢,微孔洞很难以内颈缩的方式连接,因此裂纹较难形成,从而表现出更高的断面收缩率。     

Prediction of crack paths in WCCo alloys

A crack propagating through the WCCo microstructure has to choose between paths along the binder/carbide interface and paths across binder regions. The latter paths are selected when the crack enters a binder region at a large angle from the nearest carbide interface, while the interface paths are preferred by cracks entering at a small angle. A critical angle can be defined for the switch from one type of crack path to the other. Empirical data for the area fractions of the two crack paths in widely different WCCo alloys can be accounted for by a single critical angle, φ_c = 25°. Finite element analysis of the stress field in a region of binder enclosed between carbide grains shows that the preferred site for the growth of stress-induced microvoids will move from the carbide grain flanks to the interior of the binder region when the entry angle of the crack exceeds 24°. Thus the observation of a critical angle deciding the crack path is verified by the stress field analysis and given a physical explanation in terms of the most likely site for microvoid formation.     

Path curvature in workspace and in joint space: evidence for coexisting coordinative rules in aiming

In this study we tried to establish whether point-to-point aiming movements are planned in workspace, joint space, or both. Eight right-handed subjects performed horizontal, vertical, and diagonal aiming movements on a transversal plane. Movements were performed at several speeds. Curvature variations of the hand and corresponding joint-space paths were investigated as a function of position, direction, and speed. Straightness of hand paths predominated for vertical movements but was systematically violated for horizontal and top-right to bottom-left movements. Furthermore, the hand-path curvature of the latter movements increased with speed. Joint-space paths showed more deviation from a straight line than hand paths except for top-left to bottom-right movements in which the paths were equally curved. A comparison of normalized path curvatures at the hand and joint level indicated that in aiming, the coordinative rule of straight-line production seems to apply to both workspace and joint-space planning. The present findings confirm Kawato's (1996) views that optimization processes operate concurrently at the two control levels of arm-trajectory formation under study.     

Direct Leaching of sulfides: Chemistry and applications

The sulfide minerals associated with copper, nickel, zinc, lead, and molybdenum concentrates are described according to their thermodynamic stability zones on Eh-_pH diagrams. From these zones, the chemistry associated with various thermodynamically feasible decomposition paths is discussed, and process developments associated with the most favorable decomposition paths are briefly reviewed.     

Instability and Static Liquefaction on Proportional Strain Paths for Sand at Low Stresses

The behavior of Hostun RF sand on proportional strain paths at low confining pressures (20 to 100 kPa) is considered in this paper. In such paths, a constant dilation rate is imposed during shear. The usual features of pore pressure increase (contracting material) or decrease (dilating material) are here observed depending upon whether the imposed dilation rate is respectively greater or smaller than the “natural” dilation rate at failure (as measured in a drained test). Particular attention is given to the static liquefaction phenomenon, which is seen to occur for loose as well as dense sand provided the imposed dilation rate is large enough to lead to a continuous pore pressure increase during shear. Instability tests performed at low confining pressures on proportional strain paths show that the instability line is strain path dependent. It does not coincide with the peak deviator stress line in proportional strain paths tests, in general, but does coincide with the line d2W = 0 (nil second increment of total work).     

Scanning eye movements made when viewing film: preliminary observations

Eye movements were recorded in 10 adult subjects during the viewing of fiction and nonfiction films. Individual differences in scan paths for fiction films were found to be relatively small. Generally, eyes concentrated on the screen center when looking at characters and objects in rapid motion. Scan paths through the screen were observed in special cases, for example, in the case of a dialogue between two characters. No differences emerged in scan paths for the same clip presented in black-and-white and color versions. Results are relevant for both filmmaking and research on perceptual and cognitive strategies involved in processing motion pictures.     

Self-control, symptomatology, and substance use precursors: Test of a theoretical model in a community sample of 9-year-old children.

The authors tested a theoretical model of how self-control constructs are related to psychological symptomatology and variables that predispose to involvement versus noninvolvement in substance use: willingness to use, affiliation with peers who use, and efficacy for resisting use. Data were obtained from a sample of 332 children (mean age = 9.3 years) who were interviewed in households. Structural equation modeling showed that good self-control was related to more positive well-being and less externalizing symptomatology, whereas poor self-control was related to more externalizing and to more internalizing symptomatology. Externalizing had paths to willingness and peer use, well-being had inverse paths to these variables, and poor self-control had a direct effect to lower resistance efficacy. Multiple-group analyses indicated gender differences in paths from symptomatology to predisposing factors. Implications for understanding vulnerability to substance use are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

不同应力路径下岩石细观力学性能离散元研究

岩体工程中的应力状态对围岩的稳定性具有重要影响。为研究地下巷道中岩体应力状态对围岩稳定性的影响规律,基于离散元理论,对地下巷道开挖过程的应力状态进行分析,开展了围压卸载—轴压增加、围压卸载—轴压不变和围压卸载—轴压减少3种不同卸载路径下的三轴压缩数值模拟试验,并与常规三轴压缩试验进行对比,分析了不同应力路径下的岩石宏观强度特征及细观损伤过程差异性。结果表明：强度准则和应力张量状态不受卸载路径的影响,但不同应力路径下岩体的损伤过程不同,围压卸载—轴压不变应力路径下的微观裂纹发育最密集,而围压卸载—轴压增加应力路径下的裂纹丛集速度最快。研究结果可为地下巷道开挖过程中的围岩应力卸载破坏分析提供参考。     

Measurements of trabecular bone structure in man

A quantitative analysis of trabecular bone structure is presented, based on omnidirectional distributions of paths across (a) trabeculation and (b) marrow cavities. The omnidirectional distributions, which take into account structural anisotropy, are generated from measured distributions of paths. Representative examples are given, together with values of two commonly quoted structural parameters, the ratio of endosteal surface to bone volume and percentage bone volume. Data on the biological and age variations in the third lumbar vertebra are also presented and an index of trabecular anisotropy suggested. Finally, the results are compared with those of other workers and estimates of useful skeletal parameters given.     

Preferential Flow in a Reclamation Cover: Hydrological and Geochemical Response

Evapotranspirative covers used for waste containment or land reclamation strategies are intended to function in perpetuity. Pedogenesis of the cover materials caused by biophysical processes may lead to the development of macroporosity (i.e., preferential flow paths), which will alter the hydrological response from the intended design function. Hydrometric and geochemical data were used in this study to examine the contribution of preferential flow to the hydrological response of a reclamation cover on saline-sodic shale mine overburden, in a cold semiarid environment. The hydrometric data suggest that infiltration occurs along preferential flow paths when the ground is frozen or when wet antecedent soil moisture conditions develop prior to precipitation events. Interflow is initiated during the spring snowmelt when the cover thaws and water migrates from the preferential flow paths into the soil matrix, causing a perched water table to form on the cover-shale interface. The cessation of interflow coincides with a recession of the perched water table and an increase in matric suction within the cover in response to elevated evapotranspiration demands. The chemistry and stable isotope signature of the interflow demonstrates that these waters are initially composed of fresher snowmelt water, flowing along preferential flow paths, which then transition to pre-event water dominated by higher concentration water from within the soil matrix. A numerical simulation demonstrates that macroporosity imposes a significant control on the discharge rate and cumulative volume of interflow.     

Possible explanations for trajectory curvature in multijoint arm movements.

Although the straightness of hand paths is a widely accepted feature of human multijoint reaching movement, detailed examinations have revealed slight curvatures in some regions of the workspace. This observation raises the question of whether planned trajectories are straight or curved. If they are straight, 3 possible factors can explain the observed curvatures: (a) imperfect control, (b) visual distortion, or (c) interaction between straight virtual trajectories and the dynamics of the arm. Participants instructed to generate straight movement paths produced movements much straighter than those generated spontaneously. Participants generated spontaneously curved trajectories in the frontoparallel plane, where visual distortion is not expected. Electromyograms suggested that participants generated straighter paths without an increase in arm stiffness. These findings argue against the 3 factors. It follows that planned trajectories are likely to be curved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Real-Time Connectivity Modeling of Water Distribution Networks to Predict Contamination Spread

This paper presents a new approach to analyzing water distribution networks during a contamination event. Previous computer models for predicting the extent of contamination spread in water distribution networks are demand-driven models. The new approach makes use of supervisory control and data acquisition (SCADA) data to create connectivity matrices, which encapsulate the worst-case projection of the potential spread of contamination obtained by combining the effects of all possible scenarios. Two methods for creating connectivity matrices are described, the first based on operating modes, and the second on fundamental paths. Both methods produce identical results, although the method of fundamental paths is more efficient computationally. The connectivity- and hydraulic-based approaches are compared using an example problem.     

Family Communication and Religiosity Related to Substance Use and Sexual Behavior in Early Adolescence: A Test for Pathways Through Self-Control and Prototype Perceptions.

This research tested predictions about pathways to substance use and sexual behavior with a community sample of 297 African American adolescents (M age: 13.0 years). Structural modeling indicated that parent-adolescent communication had a path to unfavorable prototypes of substance users; quality of parent-adolescent relationship had paths to good self-control, higher resistance efficacy, and unfavorable prototypes of sexually active teens; and religiosity had inverse direct effects to both substance use and sexual behavior. Self-control constructs had paths to prototypes of abstainers, whereas risk taking had paths to prototypes of drug and sex engagers and direct effects to outcomes. Prototypes had paths to outcomes primarily through resistance efficacy and peer affiliations. Effects were also found for gender, parental education, and temperament characteristics. Implications for self-control theory and prevention research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Geometric complexity and object search in infancy.

In four experiments we investigated the role of geometric path type in infants' ability to make spatial inferences about the location of a hidden object after they themselves had been moved through space. Nine-month-old infants were moved along geometrically simple paths of rotation (Experiments 1 and 2) or translation (Experiment 3) or along geometrically complex paths of combined rotation and translation (Experiment 4). In all but the fourth experiment, infants were able to retrieve an object hidden before they were moved, as long as the object was not located behind them at test time. Direct comparisons among the conditions showed that moving infants along geometrically simple paths led to significantly better performance than moving them along geometrically complex paths. We found the length of a path, the time needed to traverse it, and the likelihood of fixation of the target to be unrelated to the infants' performance. These findings are discussed in the context of theories of the development of spatial knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orientation specificity in spatial memory: What makes a path different from a map of the path?

Investigated factors that lead spatial information (SI) to be stored in an orientation-specific vs orientation-free manner. Exp 1 showed that learning paths from a small map vs learning paths directly from viewing a world lead to different functional characteristics of spatial memory. Whether the route display was presented as the path itself or as a large map of the path did not affect how the information was stored. Exp 2 examined effects of size of stimulus display, size of world, and scale transformations on how SI in maps is stored and available for use in later judgments. Exp 3 examined the effect of size on orientation specificity of the spatial coding of paths that are viewed directly. The main determinant of whether SI was stored and used in an orientation-specific manner or orientation-free manner was size of the display. Data support the view that there are distinct spatial representations (1 more perceptual and episodic and 1 more integrated and model-like) that have developed to meet different demands faced by mobile organisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)