Hierarchical population model with a carrying capacity distribution

A time- and space-discrete model for the growth of a rapidly saturating local biological population $N(x,t)$ is derived from a hierarchical random deposition process previously studied in statistical physics. Two biologically relevant parameters, the probabilities of birth, $B$, and of death, $D$, determine the carrying capacity $K$. Due to the randomness the population depends strongly on position, $x$, and there is a distribution of carrying capacities, $\Pi (K)$. This distribution has self-similar character owing to the imposed hierarchy. The most probable carrying capacity and its probability are studied as a function of $B$ and $D$. The effective growth rate decreases with time, roughly as in a Verhulst process. The model is possibly applicable, for example, to bacteria forming a "towering pillar" biofilm. The bacteria divide on randomly distributed nutrient-rich regions and are exposed to random local bactericidal agent (antibiotic spray). A gradual overall temperature change away from optimal growth conditions, for instance, reduces bacterial reproduction, while biofilm development degrades antimicrobial susceptibility, causing stagnation into a stationary state.Comment: 25 pages, 11 (9+2) figure

Application of a yeast-based assay protocol developed to monitor total oestrogenic activity induced by 17&#233-oestradiol in activated sludge supernatants from batch experiments

Batch experiments were carried out with activated sludge from laboratory reactors and a full-scale treatment plant spiked with 17β-oestradiol (E2). An oestrogen-sensitive yeast-based assay protocol, described in detail in a related publication, was used to measure reduction of E2-induced total oestrogenic activity from the sludge supernatant over a 15 d period after which the sludge was re-spiked to check for possible enhancement of reduction by pre-exposed sludge during an additional 15 d period. The reduction was generally improved by increasing sludge solids concentrations and by continuous mixing. For a 100 ngE2/ℓ spike there was >40% reduction of oestrogenic activity within 15 d, which improved to >70% by pre-exposing the sludge. The oestrogenic activity produced by a dose of 100 μgE2/ℓ was readily removed by most sludges within 15 d. However, re-spiking the activated sludge with the same E2 concentration caused some sludges to lose reduction capacity. Water SA Vol.32 (3) 2006: pp.355-36

Practical tips for communicating research findings in a gender-responsive way

This two-page publication highlights 12 key aspects that scientists working on research for development projects in agriculture and natural resource management should bear in mind to share their research findings in a gender-responsive way. A gender-responsive communications strategy must be adequately planned and budgeted for at the earliest stages of the research process, and comprises four facets: understanding your audience; showcasing relevant gender findings; sharing these findings with differentiated stakeholders through gender sensitive channels and monitoring and evaluating all these efforts for continuous improvement. This requires a good understanding of the topics that capture the interest of these stakeholders, their preferred ways of accessing your findings, capacity to interpret the information you produce, and the intended use of this information. Knowledge is power. Ensuring that research and action partners, but also the local women, men and marginalized groups who are the target beneficiaries of our research are able to equitably access our findings can support their empowerment and is an essential part of the research-for-development process

A WISE method for designing IIR filters

The problem of designing optimal digital IIR filters with frequency responses approximating arbitrarily chosen complex functions is considered. The real-valued coefficients of the filter's transfer function are obtained by numerical minimization of carefully formulated cost, which is referred here to as the weighted integral of the squared error (WISE) criterion. The WISE criterion linearly combines the WLS criterion that is used in the weighted least squares approach toward filter design and some time-domain components. The WLS part of WISE enforces quality of the frequency response of the designed filter, while the time-domain part of the WISE criterion restricts the positions of the filter's poles to the interior of an origin-centred circle with arbitrary radius. This allows one not only to achieve stability of the filter but also to maintain some safety margins. A great advantage of the proposed approach is that it does not impose any constraints on the optimization problem and the optimal filter can be sought using off-the-shelf optimization procedures. The power of the proposed approach is illustrated with filter design examples that compare favorably with results published in research literature

Mast cells in peritoneal fluid in rats with experimentally induced peritoneal adhesions.

Mast cells (MC) produce, store and release many biologically active substances, especially inflammatory factors, chemotactic substances for neutrophiles, cytokines and prostaglandins. They play very important role in fibrinosis and they are an important factor in peritoneal adhesions formation and lysis. In this study we tried to evaluate role of mast cells in peritoneal adhesions formation. We estimated number of mast cells in peritoneal fluid in rats with experimentally developed peritoneal adhesions. The number of mast cells per ml was counted in flow cytometry in specimens of peritoneal fluid taken from operated rats. The fluid was taken in standardized conditions the same for each group at the first operation and during reoperation. Peritoneal cavity was washed with 0.9% Saline solution. MC were visualized using indirect immunohistochemical method LSAB with mouse antibody. The animals were divided into 4 groups. 1 st group was control group (n=20) on which the abdomen was opened and closed without any manipulations, and the reoperation was done after 72 hours. The other groups (2, 3, 4; n=20 for each group) were operated and scarification of the partial peritoneum and serosa was performed. The rats were brought back to conscious and then were reoperated respectively after 24, 72 and 168 hours after first surgery. After the laparotomy and damage of the peritoneum we observed formation of the peritoneal adhesions between intestine loops and between intestines and damaged parietal peritoneum. Also the higher number of mast cells was observed in the groups of animals with damaged peritoneum. The highest number of peritoneal adhesions was observed in the group of animals reoperated after 72 hours. After 72 and 168 hours the higher number of MC and neutrophils was observed. The difference was statistically significant. The percentage of mast cells was increasing during the experiment duration. It was different from other cells populations which decreased after 168 hours. The MC and neutrophils were cell population which changed significantly after manipulations in peritoneal cavity. It is very probable that they play an important role in peritoneal adhesions formation

Mast cells in peritoneal fluid in rats with experimentally induced peritoneal adhesions.

Mast cells (MC) produce, store and release many biologically active substances, especially inflammatory factors, chemotactic substances for neutrophiles, cytokines and prostaglandins. They play very important role in fibrinosis and they are an important factor in peritoneal adhesions formation and lysis. In this study we tried to evaluate role of mast cells in peritoneal adhesions formation. We estimated number of mast cells in peritoneal fluid in rats with experimentally developed peritoneal adhesions. The number of mast cells per ml was counted in flow cytometry in specimens of peritoneal fluid taken from operated rats. The fluid was taken in standardized conditions the same for each group at the first operation and during reoperation. Peritoneal cavity was washed with 0.9% Saline solution. MC were visualized using indirect immunohistochemical method LSAB with mouse antibody. The animals were divided into 4 groups. 1 st group was control group (n=20) on which the abdomen was opened and closed without any manipulations, and the reoperation was done after 72 hours. The other groups (2, 3, 4; n=20 for each group) were operated and scarification of the partial peritoneum and serosa was performed. The rats were brought back to conscious and then were reoperated respectively after 24, 72 and 168 hours after first surgery. After the laparotomy and damage of the peritoneum we observed formation of the peritoneal adhesions between intestine loops and between intestines and damaged parietal peritoneum. Also the higher number of mast cells was observed in the groups of animals with damaged peritoneum. The highest number of peritoneal adhesions was observed in the group of animals reoperated after 72 hours. After 72 and 168 hours the higher number of MC and neutrophils was observed. The difference was statistically significant. The percentage of mast cells was increasing during the experiment duration. It was different from other cells populations which decreased after 168 hours. The MC and neutrophils were cell population which changed significantly after manipulations in peritoneal cavity. It is very probable that they play an important role in peritoneal adhesions formation

Professional Courses for Teacher Certification

The three lectures comprising this document are introduced with a foreword by Clifford L. Bishop and an introduction by William H. Dreier; both of the Department of Education and Psychology which sponsored the Central State Colleges and Universities (CSCU) seminar on the professional program for undergraduates leading to teacher certification and the B.A. or B.S. degree. The lecture by George W. Denemark presents A Proposed Common Professional Core for the Preparation of Teachers. He includes discussion of the context for curriculum planning and of the broad range of objectives for teacher education. In his discussion of Ideal Experiences Needed in the First Course for Undergraduates; Henry J. Hermanowicz deals with the newer systematic and descriptive studies of teaching; experiments in clinical studies of teaching by prospective teachers; and the emergence of theories of teaching. William E. Drake\u27s Needed Experiences in the Foundations Professional Sequence Course includes justification for a social philosophy course and discussion of content necessary to meet the minimum professional standards and classroom activity conducive to quality professional experience. Included are bibliographies; the major comments made at the final panel discussion; and a list of the seminar participants (20 from the host institution and 50 from 25 institutions in 12 different states). (JS

Characterizing a scientific elite: the social characteristics of the most highly cited scientists in environmental science and ecology

In science, a relatively small pool of researchers garners a disproportionally large number of citations. Still, very little is known about the social characteristics of highly cited scientists. This is unfortunate as these researchers wield a disproportional impact on their fields, and the study of highly cited scientists can enhance our understanding of the conditions which foster highly cited work, the systematic social inequalities which exist in science, and scientific careers more generally. This study provides information on this understudied subject by examining the social characteristics and opinions of the 0.1% most cited environmental scientists and ecologists. Overall, the social characteristics of these researchers tend to reflect broader patterns of inequality in the global scientific community. However, while the social characteristics of these researchers mirror those of other scientific elites in important ways, they differ in others, revealing findings which are both novel and surprising, perhaps indicating multiple pathways to becoming highly cited

How to analyse longitudinal data from multiple sources in qualitative health research : the pen portrait analytic technique

BACKGROUND: Longitudinal qualitative research is starting to be used in applied health research, having been popular in social research for several decades. There is potential for a large volume of complex data to be captured, over a span of months or years across several different methods. How to analyse this volume of data - with its inherent complexity - represents a problem for health researchers. There is a previous dearth of methodological literature which describes an appropriate analytic process which can be readily employed. METHODS: We document a worked example of the Pen Portrait analytic process, using the qualitative dataset for which the process was originally developed. RESULTS: Pen Portraits are recommended as a way in which longitudinal health research data can be concentrated into a focused account. The four stages of undertaking a pen portrait are: 1) understand and define what to focus on 2) design a basic structure 3) populate the content 4) interpretation. Instructive commentary and guidance is given throughout with consistent reference to the original study for which Pen Portraits were devised. The Pen Portrait analytic process was developed by the authors, borne out of a need to effectively integrate multiple qualitative methods collected over time. Pen Portraits are intended to be adaptable and flexible, in order to meet the differing analytic needs of qualitative longitudinal health studies. CONCLUSIONS: The Pen Portrait analytic process provides a useful framework to enable researchers to conduct a robust analysis of multiple sources of qualitative data collected over time