Bivariate frailty model for the analysis of multivariate survival time

Because of limitations of the univariate frailty model in analysis of multivariate survival data, a bivariate frailty model is introduced for the analysis of bivariate survival data. This provides tremendous flexibility especially in allowing negative associations between subjects within the same cluster. The approach involves incorporating into the model two possibly correlated frailties for each cluster. The bivariate lognormal distribution is used as the frailty distribution. The model is then generalized to multivariate survival data with two distinguished groups and also to alternating process data. A modified EM algorithm is developed with no requirement of specification of the baseline hazards. The estimators are generalized maximum likelihood estimators with subject-specific interpretation. The model is applied to a mental health study on evaluation of health policy effects for inpatient psychiatric care.

[Experimental study of survival mechanism of skin flap with subdermal vascular rete]

AIM

To determine the blood supply style and survival mechanism of skin flap with subdermal vascular rete.

MATERIAL AND METHODS

The skin flap on trunk of piglets were taken as experimental pattern. The survival length of skin flap was examined and the nuclear element distribution in the skin flap was determined by ECT.

RESULTS AND CONCLUSION

This study demonstrated that the distal portion of super-long flap with subdermal vascular rete fail to getting blood supply from its pedicle. This kind of flap is actually a combination of flap and free graft with subdermal vascular rete. This kind of super-long and super-wide flap is actually not a flap but a free skin graft. The survival of super-long and super-wide flaps with subdermal vascular rete rely on the blood supply from the wounds and their edges partially or completely. Their survival style is actually free grafting.

Violence by male partners against women during the childbearing year: a contextual analysis

OBJECTIVES

Many contextual analyses that bridge the micro-level-macro-level gap in identifying risk factors for adverse outcomes have not used methods appropriate for multilevel data. The purpose of this paper is to illustrate the application of appropriate multi-level analytic methods and discuss their implications for public health.

METHODS

A previously published individual-level model of physical violence perpetrated by male partners during the childbearing year was reanalyzed to include variables describing the neighborhoods where the women resided. Logistic regression with estimation methods of the generalized estimating equation was used for the contextual analysis. To assess the advantages of the generalized estimating equation over conventional logistic regression, both were used for the two-level model.

RESULTS

The regression coefficients from the contextual model differed from the betas obtained in the individual-level model. Not only were neighborhood-level variables related to the risk of partner-perpetrated violence, but the presence of these macro-level variables in the models modified the relationships of the individual-level variables to the risk of violence.

CONCLUSIONS

Two-level models that include individual- and community-level factors may be beneficial for purposes of explanation in public health research.

Interpersonal conflict and physical violence during the childbearing year

Reducing physical abuse directed at women by male partners is one of the nation's Year 2000 health objectives. An important target group for achieving this health objective is pregnant women. The present study examines the frequency, severity, perpetrators and psychosocial correlates of violence during the childbearing year. A panel of 275 women were interviewed 3 times during pregnancy and at 6 months postpartum. Moderate or severe violence was somewhat more common during the postpartum period than during the prenatal period--19% of women reported experiencing moderate or severe violence prenatally, compared to 25% in the postpartum period. For partner-perpetrated violence, being better educated was associated with increased risk of violence as was having had a sex partner who ever shot drugs; being older, having a confidant and having social support from friends were significant protective factors. For violence perpetrated by someone other than a male partner, having a confidant was a significant protective factor. Obstetric care providers who routinely come in contact with pregnant women, as well as emergency department staff, need to be systematically screening for violence against women. Efforts to enhance women's social support networks should be included in primary and secondary prevention programs.

[Effects of fertilization on yield of Asparagus cochinchinensis (Lour.) Merr]

The experiment revealed that the use of various kinds of fertilizers has apparent effect on the yield of Asparagus cochinchinensis during its growth period. Nitrogen fertilizer and compound fertilizer are suitable for the seeding period, while compound fertilizer, phosphorus and potassium fertilizers are suitable for the period of root forming. The quantity of fertilizer to be used depends on the growing and soil conditions.

[Determination of water soluble silicon from herbal drugs]

This article has set up a method for silicon determination by ammonium molybdate-ferrous sulfate-sodium carbonate spectrophotometry. The method is simple, convenient, quick, effective and free of the influence of phosphate ion and reducing agents such as vitamin C and so on. By this method water soluble silicon has been determined in 38 herbal drugs.

Silicon Coordination and Speciation Changes in a Silicate Liquid at High Pressures

Coordination and local geometry around Si cations in silicate liquids are of primary importance in controlling the chemical and physical properties of magmas. Pressure-induced changes from fourfold to sixfold coordination of Si in silicate glass samples quenched from liquids has been detected with (29)Si magic-angle spinning nuclear magnetic resonance spectrometry. Samples of Na(2)Si(2)O(5) glass quenched from 8 gigapascals and 1500 degrees C contained about 1.5 percent octahedral Si, which was demonstrably part of a homogeneous, amorphous phase. The dominant tetrahedral Si speciation in these glasses became disproportionated to a more random distribution of bridging and nonbridging oxygens with increasing pressure.