Nonoperative management of blunt hepatic and splenic injury in children

OBJECTIVE: The authors assessed the risks of nonoperative management of solid visceral injuries in children (age range, 4 months-14 years) who were consecutively admitted to a level I pediatric trauma center during a 6-year period ending in 1991. METHOD: One hundred seventy-nine children (5.0%) sustained injury to the liver or spleen. Nineteen children (11.2%) died. Of the 160 children who survived, 4 received emergency laparotomies; 156 underwent diagnostic computer tomography and were managed nonoperatively. The percentage of children who were successfully treated nonoperatively was 97.4%. Delayed diagnosis of enteric perforations occurred in two children. Fifty-three children (34.0%) received transfusions (mean volume 16.7 mL/kg); however, transfusion rates during the latter half of the study decreased from 50% to 19% in children with hepatic injuries, despite increasing grade of injury, and decreased from 57% to 23% in the splenic group with similar injury grade (p < 0.005, chi square test and Student's t test). CONCLUSION: Pediatric blunt hepatic and splenic trauma is associated with significant mortality. Nonoperative management based on physiologic parameters, rather than on computed tomography grading of organ injury, was highly successful, with few missed injuries and a low transfusion rate.     

Learning Curve Models of Construction Productivity

Current research into learning curve models of construction productivity is presented. Five mathematical models are identified and each of these are used to model unit rates for 65 sets of data. The correlation between predicted and actual unit rates is determined, and on this basis, it is concluded that the best predictor is a cubic model. The often cited straight‐line model is only marginally adequate. The validity of the straight‐line model is further undermined by showing that the learning rate is not a constant value. Time data for erecting and setting 466 precast concrete floor planks is used to support the conclusion that the straight‐line model is not a reliable model for predicting future performance.     

Process variable implications for residual solvent removal and polymer morphology in the formation of gentamycin-loaded poly (L-lactide) microparticles

PURPOSE: The purpose was to determine the influence of process parameters in the precipitation with a compressed antisolvent (PCA) process on the morphology and residual dichloromethane (DCM) levels in gentamycin-loaded PLA microparticles. METHODS: The three variables studied were the rate of CO2 co-flowed during the polymer and drug post-precipitation, the post-precipitation pure CO2 flush rate, and the post-precipitation CO2 flush volume. Residual DCM levels were determined from headspace gas chromatography-mass spectroscopy (GC-MS) with single ion monitoring. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to estimate the crystallinity within microparticles. DCM was extracted from drug-loaded microparticles by both supercritical CO2 extraction and vacuum drying for up to two days to determine a lower limit for solvent removal. RESULTS: Increasing either the post-precipitations CO2 flow rate or flush volume resulted in lower residual DCM levels in the microparticle. The CO2 co-flow rate showed an opposite trend. Increasing in value resulted in a higher DCM value after precipitation. XRD and DSC analysis on these samples suggest that those produced at lower CO2 co-flow rates have a higher degree of crystallinity, which increases the diffusivity of DCM through the polymer matrix. Finally, samples subjected to extended (48 hr) CO2 extraction resulted in DCM levels on the order of one to three ppm. CONCLUSIONS: Specific PCA process conditions during microparticle formation have a strong influence on the residual solvent levels within the microparticles. Polymer morphology affects the diffusivity of solvent through the polymer matrix, which in turn determines the solvent removal rates.     

Unexplained infertility: evaluation of the luteal phase; results of the National Center for Infertility Research at Michigan

OBJECTIVE: To evaluate the luteal phase in women with rigorously defined unexplained infertility. DESIGN: Prospective study. SETTING: National Center for Infertility Research at Michigan. PATIENT(S): Evaluation of 1,885 women with infertility identified 12 women who met the rigorously defined criteria for unexplained infertility: [1] infertility of > or = 24 months duration, with no male factor, anatomic-functional disorders of the reproductive tract, or immunologic infertility; [2] normal body mass index (BMI); [3] ovulatory cycles ranging from 26 to 32 days; [4] normal luteal phase determined by endometrial biopsy; and [5] normal baseline hormonal profile. Controls (n = 12) were healthy, parous women with normal ovulatory cycles, normal hormonal screen, and were matched for age and BMI to patients. MAIN OUTCOME MEASURE(S): Pattern of follicular growth rate and luteal phase hormonal profile. RESULT(S): Women with unexplained infertility did not differ in menstrual cycle characteristics, follicular growth rate or mean preovulatory follicle diameter, or endometrial biopsy dating. The mean levels of P tended to be lower in the unexplained infertility group throughout the luteal phase, but only the midluteal interval reached statistical significance. Luteal phase mean integrated P or urinary PDG levels of unexplained infertility women did not differ from those of fertile controls. The ratio of integrated E2:P also was significantly greater in women with unexplained infertility than in fertile controls. CONCLUSION(S): Women with rigorously defined unexplained infertility have subtle hormonal anomalies during the luteal phase when compared with fertile controls.     

Voronoi diagrams with barriers and on polyhedra for minimal path planning

Two generalizations of the Voronoi diagram in two dimensions (E²) are presented in this paper. The first allows impenetrable barriers that the shortest path must go around. The barriers are straight line segments that may be combined into polygons and even mazes. Each region of the diagram delimits a set of points that have not only the same closest existing point, but have the same topology of shortest path. The edges of this diagram, which has linear complexity in the number of input points and barrier lines, may be hyperbolic sections as well as straight lines. The second construction considers the Voronoi diagram on the surface of a convex polyhedron, given a set of fixed source points on it. Each face is partitioned into regions, such that the shortest path to any goal point in a given region from the closest fixed source point travels over the same sequence of faces to the same closest point.This material is based upon work supported by the National Science Foundation under grants ECS-8021504 and ECS-8351942. The second author is also supported in part by a Fulbright scholarship     

Effect of referent object familiarity on verbal learning in the sighted and the blind.

Tested whether the concrete-noun effect is due to the way in which concrete concepts are coded in semantic memory or whether the effect can be attributed to the process of generating compound spatial images, using 5 paired-associate tasks. In Exp I, with 16 sighted undergraduates and 16 congenitally blind Ss (aged 24–60 yrs), results from recall tests indicate that both groups remembered nouns with referents highly familiar to the blind better than nouns with referents of low familiarity to the blind. This effect was unexpected for the sighted because the referents of low familiarity to the blind (e.g., sky, dawn, tower) had presumably been visually experienced by the sighted. Exps II–V, with 220 undergraduates, examined why the extent to which the blind are familiar with an object predicted verbal learning for the sighted in Exp I. Results suggest that referents familiar to the blind were also familiar to the sighted. It is concluded that it is the extent of perceptual experience with a noun's referent, irrespective of the modality through which the experience is acquired, that determines ease of verbal learning. The noun lists are appended. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial interactions in binocular rivalry.

Observers tracked binocular rivalry between a pair of small, foveally viewed gratings whose orientation differed between the 2 eyes. In Exp 1, a textured annulus surrounding 1 eye's grating increased the total duration of exclusive visibility of the grating only when the grating-annulus separation was less than 0.5°. In Exp 2, observers tracked the visibility of a monocular annulus that surrounded a foveally viewed grating that was either engaged in rivalry or fused with a grating alone viewed by the other eye. The visibility of the annulus was greater when the grating it surrounded was not undergoing rivalry fluctuations. In Exp 3, the predominance of a rival grating was greater when the contours in the surrounding annulus were orthogonal to those of the rival grating. In Exp 4, total exclusive visibility of a given grating-annulus target was greater when the grating and the annulus contained the same orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schizophrenic symptoms, work adjustment, and behavioral family therapy.

Investigated work adjustment among 41 recently exacerbated patients (aged 21–42 yrs) with schizophrenia who were randomly assigned to receive either customary care alone or behavioral family therapy (BFT) and customary care. At baseline, most Ss were unemployed and evidenced poor work adjustment. Negative schizophrenic symptoms were more strongly associated with current work dysfunction than were indices of other psychopathology. At 1 yr, significantly fewer Ss participating in BFT had evidenced psychotic exacerbations. However, vocational adjustment in both groups was still poor, with few benefits of BFT on work functioning noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of phase separating systems on lyophilized hemoglobin

Polymer liquid-liquid two-phase systems offer a unique opportunity to study the mechanisms of protein stabilization during freezing and freeze-drying. Fourier transform infrared spectroscopy was used to monitor the structural integrity of recombinant hemoglobin frozen and lyophilized in the separated phases of a polyethylene glycol (PEG)-dextran system. Protein in each phase of an equilibrated biphasic PEG-dextran system experiences similar levels of structural protection against freezing stresses despite large differences in polymer concentration. This result further demonstrates previous suggestions that proteins are protected during freezing by the preferential exclusion mechanism. There are, however, distinct differences in the level of structural protection that polymers in equilibrium phases provide to proteins during lyophilization, emphasizing that the mechanisms of protein protection during freezing and drying are fundamentally different. In addition, we provide evidence that phase separation per se occurring during the course of the lyophilization cycle can be detrimental to the structural stability of a protein.     

Analysis of a lidar voxel-derived vertical profile at the plot and individual tree scales for the estimation of forest canopy layer characteristics

The goal of the current study was to develop methods of estimating the height of vertical components within plantation coniferous forest using airborne discrete multiple return lidar. In the summer of 2008, airborne lidar and field data were acquired for Loblolly pine forest locations in North Carolina and Virginia, USA, which comprised a variety of stand conditions (e.g. stand age, nutrient regime, and stem density). The methods here implement both field plot-scale analysis and an automated approach for the delineation of individual tree crown (ITC) locations and horizontal extents through a marker-based region growing process applied to a lidar derived canopy height model. The estimation of vertical features was accomplished through aggregating lidar return height measurements into vertical height bins, of a given horizontal extent (plot or ITC), creating a vertical ‘stack’ of bins describing the frequency of returns by height. Once height bins were created the resulting vertical distributions were smoothed with a regression curve-line function and canopy layers were identified through the detection of local maxima and minima. Estimates from Lorey’s mean canopy height was estimated from plot-level curve-fitting with an overall accuracy of 5.9% coefficient of variation (CV) and the coefficient of determination (R²) value of 0.93. Estimates of height to the living canopy produced an overall R² value of 0.91 (11.0% CV). The presence of vertical features within the sub-canopy component of the fitted vertical function also corresponded to areas of known understory presence and absence. Estimates from ITC data were averaged to the plot level. Estimates of field Lorey’s mean canopy top height from average ITC data produced an R² value of 0.96 (7.9% CV). Average ITC estimates of height to the living canopy produced the closest correspondence to the field data, producing an R² value of 0.97 (6.2% CV). These results were similar to estimates produced by a statistical regression method, where R² values were 0.99 (2.4% CV) and 0.98 (4.9% CV) for plot average top canopy height and height to the living canopy, respectively. These results indicate that the characteristics of the dominant canopy can be estimated accurately using airborne lidar without the development of regression models, in a variety of intensively managed coniferous stand conditions.