Nonparametric estimation of the survival function for ordered multivariate failure time data: A comparative study

In longitudinal studies of disease, patients may experience several events through a follow‐up period. In these studies, the sequentially ordered events are often of interest and lead to problems that have received much attention recently. Issues of interest include the estimation of bivariate survival, marginal distributions, and the conditional distribution of gap times. In this work, we consider the estimation of the survival function conditional to a previous event. Different nonparametric approaches will be considered for estimating these quantities, all based on the Kaplan–Meier estimator of the survival function. We explore the finite sample behavior of the estimators through simulations. The different methods proposed in this article are applied to a dataset from a German Breast Cancer Study. The methods are used to obtain predictors for the conditional survival probabilities as well as to study the influence of recurrence in overall survival.     

The relevance of the mesosomal internal structures to the phylogeny of Augochlorini bees (Hymenoptera: Halictinae)

The use of internal skeletal structures is valuable to phylogenetic reconstruction within Hymenoptera; however, these structures were not further investigated for Augochlorini. Previous phylogenetic studies of Augochlorini based only on external morphology were poorly resolved. The objectives of this work are to explore the comparative morphology of internal structures of the mesosoma and to evaluate their potential as information sources for the phylogenetic relationships within the tribe. The internal structures of the Pseudaugochlora graminea (Fabricius, 1804) mesosoma are described in detail and compared with 16 other genera. We propose 24 new character statements for the Augochlorini phylogeny based on internal structures of mesosoma. Prosternum, propleuron and meso/metafurca provided a great number of informative characters. On the other hand, the mesophragma, metanotum and propodeum were less variable. The monophyly of Augochlorini and of all genus groups was corroborated in a parsimony analysis of internal and external morphological characters. Characters derived from internal structures provided the first‐known morphological synapomorphies for the clades: Megaloptidia group + others, Neocorynura group + others and Augochlora group + Megalopta group. These characters helped to elucidate the evolution of the group when analysed together with external morphological characters.     

Bedside manners: Paradoxes of physician behavior in grand rounds

This paper explains some of the routine of grand rounds in a major Israeli teaching hospital. It focuses on paradoxical behavior of physicians and others who participate in grand rounds. Behaviors are explained as boundary marking mechanisms meant to redefine statuses in the hospital and defend the physician from threats to his status. These paradoxical behaviors also function to permit the physician to enter and depart from the more culturally marginal territories of human experience, those which people try to deny or mask in everyday life. In particular, paradoxical behavior arises when dealing with death, waste, and sex. Paradoxical behavior is seen as a means of making a space in which everyday reality is masked and turned into play, creating a boundary between the medical reality and the social world. Paradox and other aspects of the grand rounds serve to restratify and counteract structural breakdown created by the physician's entry into states of pollution.     

Variation in Endogenous Gibberellins,Abscisic Acid,and Carbohydrate Content During the Growth Cycle of Colored <Emphasis Type="Italic">Zantedeschia</Emphasis> spp., a Tuberous Geophyte

Phenologic changes and variation in the level of endogenous gibberellins (GAs), abscisic acid (ABA), carbohydrate content, and α-amylase activity were examined in colored Zantedeschia spp. cv. Cala Gold. These changes were examined in the primary bud tissues and in the attached tuber tissue during the growth cycle. Dormant tubers were dry-stored at 20°C for 3 months, planted in a phytotron, and grown under 22/16 ± 1°C. Plant development was monitored under continued irrigation until leaf senescence and tuber dormancy. GAs and ABA were extracted from the primary bud tissues, fractionated by HPLC, and analyzed using GC-SIM. Starch, glucose, soluble protein, and α-amylase activity were monitored in the tuber tissue attached to the primary bud. Endogenous changes in GAs and ABA in the primary bud were correlated with endogenous changes in carbohydrate content and α-amylase activity in the attached tuber tissue. These correlations were observed during the rest and the growth periods and were associated with developmental changes in the plant, that is, bud dormancy relaxation, bud growth, and inflorescence differentiation. ABA content decreased and a transient pulse of GA was measured in the primary bud concomitantly with the onset of shoot elongation in dry tubers during storage, before planting. The sharp increase of GAs in the bud preceded inflorescence differentiation as observed in dissected apices by about 15 days, as well as the increase in α-amylase activity in the attached tuber tissue. A steep decrease in starch level was measured in the tuber after planting, concomitantly with massive plant growth. These findings suggest a possible involvement of gibberellin in the initiation of α-amylase activity during dormancy relaxation in colored Zantedeschia and in the autonomous induction of flowering.     

Crawling of worms

The mechanics of a worm crawling along a flat surface is analyzed. The external forces of friction and gravity, and the internal pressure and tension, are taken into account. An equation of motion is formulated, and solutions are sought in which both the tension and the linear density are required to lie between prescribed bounds. Pulse and periodic travelling wave solutions are constructed. The maximum crawling velocity is determined, as well as the wave form which achieves it. Comparison of the results with experimental observations shows that the theory yields a maximum crawling velocity which is much larger than the observed velocity. Therefore, the theory is changed to require that the time rate of change of tension be less than a prescribed bound, rather than that the tension be bounded. With this modification, the theory agrees fairly well with the observations.     

Enhanced shoot and cormlet proliferation in liquid cultured gladiolus buds by growth retardants

Gladiolus bud explants propagated in agitated liquid medium, in the presence of the growth retardants daminozide, ancymidol, paclobutrazol or Majic, proliferated into massive bud aggregates without leaves. The buds developed into protocorms and after subculture to agar-solidified medium formed cormlets 8–10 mm in diameter. The corms were not dormant and, after transplanting to pots in the greenhouse, developed into plantlets, 5–6 months after explant isolation.     

Ethylene and the geotropic response of lateral branches in peanuts (Arachis hypogaea L.)

The prostrate growth habit of runner-type peanut plants changedwhen treated with the ethylene-releasing compound CEPA: thehorizontal branches became plagiotropically oriented and theplant assumed a bushy form. Treatment with CEPA caused a markedincrease in ethylene evolution for about a week, which thendecreased to the level of the control. Nevertheless, the branchesmaintained their newly assumed plagiotropic orientation. Ethylene evolution from isolated branch tips correlated withtheir age and orientation, being highest in old plagiotropicand lowest in old diatropic branches. Light intensity and qualitywhich caused plagiotropic orientation of branches also causedan increase in ethylene evolution, while ethylene evolutionwas lowest under light conditions favouring diatropic orientation.Along with the changes to plagiotropic orientation by CEPA,an increase in GA-like substances and a decrease in growth inhibitorswas observed in extracts from treated plants. (Received October 7, 1975; )     

Rescue of interspecific lens hybrids by means of embryo culture

A two-stage in vitro technique was established for the development of interspecific hybrid embryos in the genus Lens. The culture of 14-day-old fertilized ovules on MS medium supplemented with zeatin, followed by the release of the embryos from the ovular integuments, allowed the development of viable and vigorous plants.     

Minimum leaching scheduling of nitrogen fertilization and irrigation

This paper develops and applies a dynamic mathematical model for optimal scheduling of nitrogen fertilization and irrigation that minimizes nitrogen leaching subject to a target level of yield. The analysis assumes a single crop grown during a single growing season of a given length. It is shown that substitution of water for nitrogen along a given plant growth path decreases nitrogen leaching and, therefore, groundwater contamination. It is proved that a minimum leaching solution to the optimization problem is obtained with a single nitrogen application at the beginning of the season and irrigation scheduling that maintains a wet soil throughout the growing period. A numerical example utilizing experimental data for an irrigated summer corn in Israel confirms and quantifies the analytical findings.