Open Capture–Recapture Models with Heterogeneity: II. Jolly–Seber Model

Summary Estimation of abundance is important in both open and closed population capture–recapture analysis, but unmodeled heterogeneity of capture probability leads to negative bias in abundance estimates. This article defines and develops a suite of open population capture–recapture models using finite mixtures to model heterogeneity of capture and survival probabilities. Model comparisons and parameter estimation use likelihood‐based methods. A real example is analyzed, and simulations are used to check the main features of the heterogeneous models, especially the quality of estimation of abundance, survival, recruitment, and turnover. The two major advances in this article are the provision of realistic abundance estimates that take account of heterogenetiy of capture, and an appraisal of the amount of overestimation of survival arising from conditioning on the first capture when heterogeneity of survival is present.     

Application of Modeling to Scale-up Dissolution in Pharmaceutical Manufacturing

Liquid mixing scale-up in pharmaceutical industry has often been based on empirical approach in spite of tremendous understanding of liquid mixing scale-up in engineering fields. In this work, we attempt to provide a model-based approach to scale-up dissolution process from a 2 l lab-scale vessel to a 4,000 l scale vessel used in manufacturing. Propylparaben was used as a model compound to verify the model predictions for operating conditions at commercial scale that would result in similar dissolution profile as observed in lab scale. Geometric similarity was maintained between both of the scales to ensure similar mixing characteristics. We utilized computational fluid dynamics (CFD) to ensure that the operating conditions at laboratory and commercial scale will result in similar power per unit volume (P/V). Utilizing this simple scale-up criterion of similar P/V across different scales, results obtained indicate fairly good reproducibility of the dissolution profiles between the two scales. Utilization of concepts of design of experiments enabled summarizing scale-up results in statistically meaningful parameters, for example −90% dissolution in lab scale at a given time under certain operating conditions will result in 75–88% at commercial scale with 95% confidence interval when P/V is maintained constant across the two scales. In this work, we have successfully demonstrated that scale-up of solid dissolution can be done using a systematic process of lab-scale experiments followed by simple CFD modeling to predict commercial-scale experimental conditions.     

Biofeedback,voluntary control,and human potential

This paper examines some of the philosophical and scientific relationships involving self-control, voluntary control, and psychophysiologic self-regulation. The role of biofeedback in mediating conscious and unconscious processes is explored. Demonstrations of superior voluntary control and its relationship to belief, confidence, and expectation are examined. Biofeedback demonstrates the potential of control to oneself, creating confidence in one's ability to establish enhanced and peak performance in athletics, education, and psychophysiologic therapy. Emphasis is placed on the power of images in all human functioning, and in enhancing human potential.Presidential address presented at the meetings of the Biofeedback Society of America, March 23, 1986, San Francisco.     

Reticulated hyaluronan hydrogels: a model for examining cancer cell invasion in 3D.

The extracellular polysaccharide hyaluronan (HA) controls cell migration, differentiation and proliferation, and contributes to the invasiveness of human cancers. The roles of HA cell surface receptors and hyaluronidases (HAses) in this process are still controversial. In order to investigate their involvement in cancer pathogenesis, we developed a reticulated HA hydrogel, a three-dimensional matrix in which cells can invade and grow. We have studied thirteen cell lines, from primary tumors or metastases, that migrated into the HA hydrogel and proliferated giving rise to clusters and colonies. The number of colonies, which reflects tumor cell invasiveness, ranged from 7 to 193 after 5 days of culture. Invasion was dependent on the production of HAse as well as other factors. Optimal colonization occurred when cells released HAse, lacked HA-binding sites and did not secrete HA. Moreover, we describe for the first time a HAse activity at physiological pH that may be responding to the confinement of the enzyme in a three-dimensional structure. We show here that this reticulated matrix provides a three-dimensional model for investigating mechanisms involved in malignant invasion.     

Problems with the use of terracotta clay saucers as phosphorus-diffusing substrata to assess nutrient limitation of epilithic algae

1. We examined the diffusion properties of terracotta clay saucers, of types often used as components in phosphorus-diffusing substrata for investigating nutrient limitation of epilithic algae.
2. Laboratory experiments showed that phosphorus diffusion was low and inconsistent (0.06–2.6 mg P day⁻¹) through clay saucers filled with agar containing orthophosphate. Similarly, in situ release of phosphorus from two types of terracotta clay saucers (Australian and Italian) was variable (2–8 mg P day⁻¹; 5–25%) under three flow regimes (0, 0.1 and 0.3 m s⁻¹) over 30 days, with most phosphorus being released during the first day. Clogging of pores by agar appears to prevent the diffusion of phosphorus through the terracotta clay saucers. However, the two types of terracotta clay saucer also irreversibly sorbed large quantities of phosphorus (40–140 mg P).
3. Individual saucers can have markedly different physical and chemical properties both within and among terracotta types. Terracotta saucers also contain large quantities of iron, calcium and aluminium that are known binding agents for phosphorus. Variability in saucer composition and diffusion properties makes treatments difficult to replicate and weakens comparisons between studies that have used terracotta with different clay composition and manufacture.
4. We recommend that phosphorus-diffusing substrata should not be constructed from terracotta clay components.     

Crystalline inclusions in Bacillus thuringiensis

Crystalline inclusion bodies resembling those seen in Clostridium cochlearium were detected in cultures of Bacillus thuringiensis infected with bacteriophage.     

Metal ion-biomolecule interactions. II. Methylmercuration of the deprotonated amino groups in adenine,guanine, and cytosine derivatives,and its relationship to amino group acidity

Proton nmr spectroscopic evidence is presented for methylmercury(II) binding to the deprotonated amino groups in adenosine, 9-methyladenine, guanosine, 1-methylguanosine, and cytidine under basic conditions. Except for the guanosine case, ¹H nmr spectra of the products from aqueous or ethanolic 1:1 mixtures of substrate and MeHgOH are consistent with methylmercuration of the deprotonated amino groups. Guanosine undergoes initial binding of MeHg to N₁, and a second equivalent of MeHgOH is necessary to effect amino binding. The nmr spectra of the complexed adenine derivatives suggest that different geometrical isomers exist in (CD₃)₂SO solution, reflecting the partial double bond character of the C₆N bond in these systems. Using a correlation relating the magnitude of the ¹⁹⁹Hg-¹H coupling constant (J) for MeHg-ligand complexes with the ligand pK_a (J = ?3.88 pK_a + 248.5, extending over 13 pK units, based on a variety of N and O donor ligands), estimates (± 0.3 pK unit) of the pK_as of the amino groups of the above substrates have been made. In this way, pK_a values of 15.5 (cytidine), 17.0 (adenosine and 9-methyladenine), 15.1 (guanosine), and 14.9 (1-methylguanosine) are obtained. In the cases where comparisons with literature pK_a data can be made, good agreement is found.     

The BH3-only protein bid is dispensable for DNA damage- and replicative stress-induced apoptosis or cell-cycle arrest

Bid, a caspase-activated proapoptotic BH3-only protein, is essential for Fas-induced hepatocyte destruction. Recent studies published in Cell produced conflicting results, indicating that loss of Bid either protects or enhances apoptosis induced by DNA damage or replicative stress. To resolve this controversy, we generated novel Bid-deficient mice on an inbred C57BL/6 background and removed the drug-selection cassette from the targeted locus. Nine distinct cell types from these Bid-deficient mice underwent cell-cycle arrest and apoptosis in a manner indistinguishable from control WT cells in response to DNA damage or replicative stress. Moreover, we found that even cells from the original Bid-deficient mice responded normally to these stimuli, indicating that differences in genetic background or the presence of a strong promoter within the targeted locus are unlikely to explain the differences between our results and those reported previously. We conclude that Bid has no role in DNA damage- or replicative stress-induced apoptosis or cell-cycle arrest.     

Predation on Moose Calves by European Brown Bears

Abstract: In North America, brown bears (Ursus arctos) can be a significant predator on moose (Alces alces) calves. Our study in Sweden is the first in which brown bears are the only predator on moose calves. Bears and moose occurred at densities of about 30/1,000 km² and 920/1,000 km², respectively, and bears killed about 26% of the calves. Ninety-two percent of the predation took place when calves were <1 month old. Bear predation was probably additive to other natural mortality, which was about 10% in areas both with and without bears. Females that lost their calves in spring produced more calves the following year (1.54 calves/F) than females that kept their calves (1.11 calves/F), which reduced the net loss of calves due to predation to about 22%.