Cellular automaton for bacterial towers

A simulation approach to the stochastic growth of bacterial towers is presented, in which a non-uniform and finite nutrient supply essentially determines the emerging structure through elementary chemotaxis. The method is based on cellular automata and we use simple, microscopic, local rules for bacterial division in nutrient-rich surroundings. Stochastic nutrient diffusion, while not crucial to the dynamics of the total population, is influential in determining the porosity of the bacterial tower and the roughness of its surface. As the bacteria run out of food, we observe an exponentially rapid saturation to a carrying capacity distribution, similar in many respects to that found in a recently proposed phenomenological hierarchical population model, which uses heuristic parameters and macroscopic rules. Complementary to that phenomenological model, the simulation aims at giving more microscopic insight into the possible mechanisms for one of the recently much studied bacterial morphotypes, known as "towering biofilm", observed experimentally using confocal laser microscopy. A simulation suggesting a mechanism for biofilm resistance to antibiotics is also shown

Change – social and personal: Thomas and Znaniecki’s The Polish Peasant for the study of present-day change in global higher education

The present work represents an extrapolation of W.I. Thomas and Florian Znaniecki’s study, The Polish Peasant in Europe and America, on behalf of the development of sociological theory. The article focuses on careers and institutions in higher education. The curriculum vitae serves as the novel human document by which to investigate both social and personal change. Academic careers are studied by virtue of their objective and subjective dimensions. Objectively, the institution of education is revealed through the shifting expectations that govern work in academia in specific historical times (indicated by the cohort in which academics earned their Ph.D.s) and in specific socially bound places (indicated by the type of university in which academics work). Major social change in education is likely to spell personal change for the way in which people subjectively experience the contemporary academic career. The data come from U.S.-based academics; parallel transformational changes are observable globally. The global change discussed in the work centres on the diffusion and institutionalization of the research role. The sources and consequences of this change are problematic. Akin to Thomas and Znaniecki’s larger analytic aims, patterns of change are used inductively to formulate theory: the paper culminates by postulating a theory of increasing tendencies in the way knowledge is produced in higher education institutions throughout the world

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

The importance of measuring impact for social investment. Case of children focused programs in polish context

The objective of this paper is to examine what are the processes of impact measurements in service organizations, foundations and social investors and to learn whether organisations measure their impact, how do they do it, and whether their impact range has any influence on the financing side of their actions. What are the misalignments of expectations between investors and investees regarding the impact measurement? If there is a mismatch between what investors want and what investees can implement, is there a way to change a paradigm? This research had an exploratory character and was conducted in the context of organisations working in Poland as well as foundations with global outreach focused on children development and education

Determination of Young's modulus of samples of arbitrary thickness from force distance curves: numerical investigations and simple approximate formulae

We present simple expressions for load required to indent a layer of arbitrary thickness with a conical, paraboloidal or cylindrical punch. A rigid substrate underneath the sample leads to an increase of load required for indentation. This effect has to be corrected for to prevent overestimation of Young's modulus from indentation measurements, such as force - distance curves recorded with the Atomic Force Microscope (AFM). The problems of the frictionless contact of an axisymmetric punch and an isotropic, linear-elastic layer are reducible to Fredholm integral equations of the second kind. We solved them numerically and used the Remez algorithm to obtain piecewise polynomial approximations of the load - indentation relation for samples that are either in frictionless contact with the rigid substrate or bonded to it. Their relative error due to approximation is negligible and uniformly spread. Combining the numerical approximations with asymptotic solutions for very thin layers, we obtained equations appropriate for samples of arbitrary thickness. They were implemented in a new version of AtomicJ, our free, open source application for analysis of AFM recordings

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

Square Root Raised Cosine Fractionally Delaying Nyquist Filter – Design and Performance Evaluation

In this paper we propose a discrete-time FIR (Finite Impulse Response) filter which is meant to be applied as a square root Nyquist filter and fractional delay filter simultaneously. The filter enables to substitute for a cascade of square root raised cosine (SRRC) Nyquist filter and fractional delay filter in one device/algorithm. The aim is to compensate for transmission delay in digital communication system. Performance of the filter in the role of a matched filter is evaluated using a newly defined energetic ISI (Intersymbol Interference) measure and ability of the filter to completely eliminate the ISI involved by fractional delay of symbol shaping filter in transmitter or by channel delay. Considerations and results of the contribution are documented by suitable eye-diagrams and the SRRC filter responses

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

Neurodegenerations are diseases of the present and the future

Neurodegenerations are diseases of the present and the future. As the human population grows, the number of people suffering from neurodegenerative diseases will increase. Neurodegenerations diseases are Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, spinocerebellar ataxia, spinal muscular ataxia), sporadic (amyotrophic lateral sclerosis) or  infectious (prion disease). Nerve cells (neurons) can’t regenerate and therefore die under the influence of pathological factors. Neurodegenerations diseases can be serious or life-threatening. It depends on the type. Drags and treatments may help improve symptoms, relieve pain, and increase mobility