Averaging correlation coefficients: Influence of heterogeneity and set size.

Silver and Dunlap (1987) recently investigated two methods for averaging correlations: (a) simple average of rs, and (b) average of Fisher's z transformations of r backtransformed to r. The latter method was found to be less positively biased than the simple average of rs was negatively biased. The current study extends these results by demonstrating that the z-transformation method is less susceptible to heterogeneity in the correlations that are averaged, but that the absolute magnitude of bias in the two approaches becomes similar as set size increases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mean size of plate martensite: influence of austenite grain size,partitioning, and transformation heterogeneity

The evolution of transformation microstructure during martensite transformation is revisited. The influence of “spread” heterogeneity on current partitioning concepts is assessed. Following that, a method to infer details of martensite transformation in an average austenite grain is described. The results indicate that the mean martensite plate size may remain constant up to a significant extent of grain transformation. Moreover, it is found that the mean martensite plate volume in fine grain austenite is proportionally larger than that observed with coarse grain austenite, and these effects are ascribed to autocatalysis. Finally, a transformation model is derived which accurately describes the data up to V_v = 0.65, irrespective of austenite grain size.     

Oxidized low density lipoprotein--an extreme example of lipoprotein heterogeneity

Toilet training is as necessary a developmental step for the child with chronic illness as it is for the healthy child. Helping families and children to achieve this task, despite the demands of the illness, may require modification of usual techniques. Assessment of readiness and impediments to toilet training along with suggested intervention approaches are addressed. Case examples demonstrate individualization to specific children's needs.     

Diurnal heterogeneity in structure and function of low density lipoproteins of normolipidemic males

Structural changes in low density lipoproteins (LDL) have been shown to alter their metabolism and atherogenic potential. We investigated the diurnal changes in size and composition of LDL in seven healthy, non-obese, normolipidemic male volunteers consuming a standard diet (14.5% protein, 31.9% fat, 53.6% carbohydrate and 383 mg cholesterol/day) and continuing their daily routine. The food was divided into three meals and three snacks, and blood samples were obtained at 7 AM (after 12 h fasting), noon, 8 PM, midnight and 3 AM. LDL were isolated by both sequential and density gradient ultracentrifugation (d = 1.019 - 1.050 g/ml), and analyzed for lipids, apolipoproteins, size, and affinity to LDL receptors. Diurnal LDL preparations differ from fasting LDL in both chemical and physical parameters. The former get richer in triglyceride (TG/cholesterol weight ratio 0.23 vs. 0.16), larger in diameter (21.2 +/- 0.2 vs. 22.4 +/- 0.1 nm), and enriched in a more buoyant fraction (74.0 +/- 4.6 vs. 41.9 +/- 3.8% of LDL cholesterol in d = 1.019 - 1.035 g/ml). These structural changes in LDL were associated with enhanced affinity to LDL receptors in both human skin fibroblasts and HepG2 cells, as demonstrated by competition experiments with fasting human 125I-LDL. The observed diurnal heterogeneity in both the structure and the function of LDL may be attributed to the absorptive state as it did not occur during prolonged fasting. These diurnal changes may be important for better understanding LDL metabolism in vivo and for the elucidation of the atherogenic process.     

Low density lipoproteins (LDL) heterogeneity and intravenous fat in neonates

BACKGROUND: The properties of iv-fat emulsions are similar to those of triglyceride-rich plasma lipoproteins and rapidly hydrolyzed by lipoprotein lipase. Neonates frequently do not tolerate iv-fat because of low levels of the key enzymes for fat metabolism. PURPOSE OF THE STUDY: We examined the effect of iv-fat therapy on LDL subclass distribution of 20 neonates unable to tolerate enteral feeding. METHODS: Particle size was determined by non-denaturing gradient gel electrophoresis. RESULTS: The LDL size distribution profiles at baseline showed unexpected diversity in the position of the major lipoprotein peak with three different profiles identified by peak position; profile I with a major peak of large-sized LDL (26.3-28.2 nm), profile II with a major peak at 25.2-26.7 nm and profile III with a major peak of small-sized particles (24.9-25.6 nm). None of the profiles fit the classical LDL pattern A or B found in adult plasma since the skewness associated with the adult pattern was not present. With iv fat feeding and enteral nutrition, no major shift in peak position was observed, even though plasma triglyceride and apo B concentrations increased suggesting that there was an increased number of LDL particles rather than an increase in the size of particles. CONCLUSION: The constancy of the LDL peak position in the face of increases in plasma triglyceride and apo B concentrations during iv fat and the onset of enteral nutrition in neonates suggests that other metabolic events, such as hormone status and lipid and transfer protein activities need to be considered.     

Nanostructured Ni-Co alloys with tailorable grain size and twin density

We present an experimental approach to systematically produce nanostructures with various grain sizes and twin densities in the Ni-Co binary system. Using electrodeposition with various applied current densities and organic additive contents in the deposition bath, we synthesize nanostructured fcc and hcp solid solutions with a range of compositions. Due to the low stacking fault energy (SFE) of these alloys, growth twins are readily formed during deposition, and by adjusting the deposition conditions, a range of twin boundary densities is possible. The resulting nanostructured alloys cannot be described by a single characteristic length scale, but instead must be characterized in terms of (1) a true grain size pertaining to general high-angle grain boundaries and (2) an effective grain size that incorporates twin boundaries. Analysis of Hall-Petch strength scaling for these materials is complicated by their dual length scales, but the hardness trends found in Ni-80Co are found to be roughly in line with those seen in pure nanocrystalline nickel.     

Preparation of ceria with large particle size and high appearance density

Cerium is one of the most abundant rare earth elements in both bastnasite and monazite. Ceria has been widely used in optical, catalytic, electrolyte, and sensor materials, with unique performances. With the development of functional materials, great interest has been focused on the synthesis and characterization of specific fine/mesoporous ceria powder. In this study, the modified precipitation and recrystallization processes combined with a controlled calcination process for fabricating the ceria with large particle size and high appearance density was reported. During precipitation, a certain amount of mineral acid such as nitric acid served as an additive, to adjust the precipitation and crystallization processes of cerium oxalates. An appropriate acidic condition could lead the process into the Oswald ripening stage and made the particles become bigger. Thus, the appearance density of powder was increased. The optimized conditions, such as the temperature, feeding speed, type and concentration of mineral acids, and the concentration of cerium-contained stock solution, were investigated and evaluated.     

Platelet antigens: immunology and immuno-allergology

Platelet immunology allows the understanding of clinical findings in a genetic and serologic basis. Blood platelets bear common antigens and same specific antigens, classified in five groups (HPA 1 to 5), that are localized on membrane glycoproteins Ia, Ib alpha, IIb and IIIa. Antiplatelet autoimmunization is generally due to IgG antibodies against membrane complexes IIb/IIIa or Ib/lX. Antiplatelet alloimmunization, clinically resulting in Posttransfusion Purpura and Neonatal Thrombocytopenia is more frequently associated with anti-IIb/IIIa antibodies, either anti-HPA-1a or HPA-1b. Finally, platelet participation in immunoallergic reactions is discussed, focusing both platelet activation by allergen itself and platelet recruitment by other inflammatory cells.     

Hepatitis C virus density heterogeneity and viral titre in acute and chronic infection: a comparison of immunodeficient and immunocompetent patients

OBJECTIVES: To assess nosocomial infections in a burn care centre, to identify patients' infection risk factors at the time of admission and factors of monthly variations of infection incidence. STUDY DESIGN: Prospective survey, from October 1992 to September 1993. PATIENTS AND METHOD: The study included 140 patients staying for more than two days in a 22-bed burn unit. Nosocomial infection criteria were derived from the 1988 CDC criteria. Incidence rates of infection were calculated. Infected and noninfected patients were compared. Each monthly infection incidence was compared with six unit activity indicators. RESULTS: Fifty-six patients developed 132 infections. The overall incidence was 94%. Incidence density was 25 infections per 1,000 days of care. The distribution of infected sites was: skin (30%), intravascular catheters (25%), blood (22%), urinary tract (18%), respiratory tract (5%). The most frequent pathogens were Pseudomonas sp (49%), Staphylococcus sp (18%), Escherichia coli (18%), and Streptococcus faecalis (10%). They were characterized by a good antibiotic sensitivity. Each common burn severity index was predictive of nosocomial infections. Facial, perineal and respiratory lesions were also linked to infection. There was a positive correlation between the peak of nosocomial infections in the unit during a month and the peak of activity during the foregoing one. CONCLUSION: Incidence rates of infection were high, as 40% of the population was concerned. Choosing reliable infection criteria was the most difficult problem to solve.     

Gonioscopy: evaluation and interpretation

Gonioscopy is the ocular health examination technique which offers to the practitioner the means to directly study the anterior chamber angle. Its uses are numerous and include glaucoma classification, predilation angle evaluation, and the presence of iris tumors, foreign bodies and anterior synechiae. Since a meaningful gonioscopic examination depends upon the examiner's recognition of the chamber landmarks, a detailed analysis of each structural element is presented. In addition, the techniques for performing gonioscopy with the popular lens types are viewed as is the system for interpretation and recording.     

Determination of the optimum current density during vacuum-arc remelting to ensure the minimum macrochemical heterogeneity in ingots

A technique is developed to predict (with an accuracy sufficient for practice) the optimum linear current density, which ensures the formation of a high-quality ingot without segregation defects, during vacuum-arc remelting of a nickel superalloy using its chemical composition.     

Determinants of radial bone density as measured by PQCT in pre- and postmenopausal women: the role of bone size

OBJECTIVE: To investigate characteristics of children and adolescents with a history of combined pharmacotherapy (CPT) and compare them with a group with no history of CPT. METHOD: Eighty-three consecutive admissions to a residential treatment center were divided into a CPT and a no-CPT group based on treatment history and compared by chart review. Prevalence of lifetime psychiatric medication use and CPT exposure were assessed. Demographic, diagnostic, treatment, behavioral, and medication variables were compared across the two groups. RESULTS: Medication use was present in the treatment history for 89.2% and a history of CPT was found for 60.3% of subjects. Admission to current placement from inpatient psychiatry, lifetime number of psychiatric placements, lifetime number of psychiatric diagnoses, and nonseizure neuropsychiatric comorbidity were significantly associated with CPT. Aggression and neuroleptic use were also significantly associated with CPT. Admission psychiatric diagnostic comorbidity was not associated with CPT. CONCLUSIONS: A high prevalence of psychiatric medication use and CPT was found in this population. Variables assessing illness severity, aggressive behavior, and nonseizure neuropsychiatric comorbidity may identify youths in psychiatric treatment settings with a high prevalence of past or current CPT exposure. Further research on the CPT of aggression is warranted.     

粉末注射成形中注射工艺参数对注射坯尺寸和密度的影响

通过单因子试验法研究了注射成形中注射温度、注射压力、体积流率、保压压力对注射坯尺寸和密度的影响,发现注射工艺参数的变化对注射坯的尺寸收缩、密度变化的影响很大且具有规律性;其中,注射温度和注射压力是对注射坯各项性能影响最大的参数。注射坯尺寸的变化对产品最终尺寸影响很小,可以忽略;而注射坯密度的变化对烧结后的尺寸精度影响很大。因此,在生产中要注意通过控制注射工艺参数来控制注射坯的密度以提高产品的尺寸精度。