Symbol representations and signal dynamics in evolving droplet computers

We investigate several evolutionary computation approaches as a mechanism to “program” networks of excitable chemical droplets. For this kind of systems, we assigned a specific task and concentrated on the characteristics of signals representing symbols. Given a Boolean function as target functionality, 2D networks composed of 10 × 10 droplets were considered in our simulations. Three different set-ups were tested: Evolving network structures with fixed on/off rate coding signals, co-evolution of networks and signals, and network evolution with fixed but pre-evolved signals. Evolutionary computation served in this work not only for designing droplet networks and input signals but also to estimate the quality of a symbol representation: we assume that a signal leading to faster evolution of a successful network for a given task is better suited for the droplet computing infrastructure. Results show that complicated functions like XOR can evolve using only rate coding and simple droplet types, while other functions involving negations like the NAND or the XNOR function evolved slower using rate coding. Furthermore we discovered symbol representations that performed better than the straight forward on/off rate coding signals for the XNOR and AND Boolean functions. We conclude that our approach is suitable for the exploration of signal encoding in networks of excitable droplets.     

A novel approach to predict the stability limits of combustion chambers with large eddy simulation

Lean premixed combustion,which allows for reducing the production of thermal NOx,is prone to
combustion instabilities.There is an extensive research to develop a reduced physical model,which
allows-without time-consuming measurements-to calculate the resonance characteristics of a
combustion system consisting of Helmholtz resonator type components （burner plenum,combustion
chamber）.For the formulation of this model numerical investigations by means of compressible Large
Eddy Simulation （LES） were carried out.In these investigations the flow in the combustion chamber is
isotherm,non-reacting and excited with a sinusoidal mass flow rate.Firstly a combustion chamber as a
single resonator subsequently a coupled system of a burner plenum and a combustion chamber were
investigated.In this paper the results of additional investigations of the single resonator are
presented.The flow in the combustion chamber was investigated without excitation at the inlet.It
was detected,that the mass flow rate at the outlet cross section is pulsating once the flow in the
chamber is turbulent.The fast Fourier transform of the signal showed that the dominant mode is at
the resonance frequency of the combustion chamber.This result sheds light on a very important
source of self-excited combustion instabilities.Furthermore the LES can provide not only the damping
ratio for the analytical model but the eigenfrequency of the resonator also.     

Accumulation of dead cells from contact killing facilitates coexistence in bacterial biofilms

Bacterial communities are governed by a wide variety of social interactions, some of which are antagonistic with potential significance for bacterial warfare. Several antagonistic mechanisms, such as killing via the type VI secretion system (T6SS), require killer cells to directly contact target cells. The T6SS is hypothesized to be a highly potent weapon, capable of facilitating the invasion and defence of bacterial populations. However, we find that the efficacy of contact killing is severely limited by the material consequences of cell death. Through experiments with Vibrio cholerae strains that kill via the T6SS, we show that dead cell debris quickly accumulates at the interface that forms between competing strains, preventing physical contact and thus preventing killing. While previous experiments have shown that T6SS killing can reduce a population of target cells by as much as 10⁶-fold, we find that, as a result of the formation of dead cell debris barriers, the impact of contact killing depends sensitively on the initial concentration of killer cells. Killer cells are incapable of invading or eliminating competitors on a community level. Instead, bacterial warfare itself can facilitate coexistence between nominally antagonistic strains. While a variety of defensive strategies against microbial warfare exist, the material consequences of cell death provide target cells with their first line of defence.     

Automatic identification of bacterial types using statistical imaging methods

The objective of the current study is to develop an automatic tool to identify microbiological data types using computer-vision and statistical modeling techniques. Bacteriophage (phage) typing methods are used to identify and extract representative profiles of bacterial types out of species such as the Staphylococcus aureus. Current systems rely on the subjective reading of profiles by a human expert. This process is time-consuming and prone to errors, especially as technology is enabling the increase in the number of phages used for typing. The statistical methodology presented in this work, provides for an automated, objective and robust analysis of visual data, along with the ability to cope with increasing data volumes.     

The results of performance measurements of field‐aged crystalline silicon photovoltaic modules

This paper presents the results of electrical performance measurements of 204 crystalline silicon‐wafer based photovoltaic modules following long‐term continuous outdoor exposure. The modules comprise a set of 53 module types originating from 20 different producers, all of which were originally characterized at the European Solar Test Installation (ESTI), over the period 1982–1986. The modules represent diverse generations of PV technologies, different encapsulation and substrate materials. The modules electrical performance was determined according to the standards IEC 60891 and the IEC 60904 series, electrical insulation tests were performed according to the recent IEC 61215 edition 2. Many manufacturers currently give a double power warranty for their products, typically 90% of the initial maximum power after 10 years and 80% of the original maximum power after 25 years. Applying the same criteria (taking into account modules electrical performance only and assuming 2·5% measurement uncertainty of a testing lab) only 17·6% of modules failed (35 modules out of 204 tested). Remarkably even if we consider the initial warranty period i.e. 10% of P_max after 10 years, more than 65·7% of modules exposed for 20 years exceed this criteria. The definition of life time is a difficult task as there does not yet appear to be a fixed catastrophic failure point in module ageing but more of a gradual degradation. Therefore, if a system continues to produce energy which satisfies the user need it has not yet reached its end of life. If we consider this level arbitrarily to be the 80% of initial power then all indications from the measurements and observations made in this paper are that the useful lifetime of solar modules is not limited to the commonly assumed 20 year. Copyright © 2008 John Wiley & Sons, Ltd.     

Highly emissive nano rod-in-rod heterostructures with strong linear polarization

We report the synthesis of CdSe/CdS rod in rod core/shell heterostructures. These rods, synthesized using a seeded-growth approach, show narrow distributions of rod diameters and lengths and exhibit high emission quantum efficiencies and highly polarized emission. The degree of polarization is controlled by the inner core rod dimensions, and it is equal or up to 1.5 times higher than the polarization of equivalent sphere in rod systems. Using the method of photoselection we measure the polarization anisotropy at different excitation wavelengths and study the interplay between electronic contribution and dielectric effects in determining the absorption and emission polarization.     

Application of waves for remediation of contaminated aquifers

A theory developed suggested that significant displacement of solute in saturated porous media results from the propagation of compression waves. Four independent one-dimensional experimental setups and a variety of laboratory methods were used to confirm the predictions of the theory, specifically aimed at developing a novel method of inducing compression waves for use in remediation of contaminated aquifers. Compaction and shock waves were emitted through granular porous media saturated with saline water. The changes in solute concentration at observation points along the propagating wave were used to verify the validity of theory. The first setup was designed mainly to provide a qualitative assessment (i.e., changes in pressure due to the propagating wave were not recorded). In situ quantitative measurements of the pressure and electrical conductivity profiles along a sand column were done with the second and third experimental setups, respectively, to short and long shock waves. In the fourth setup, solute displacement was visualized by X-ray absorption. The findings were consistent with the theory in all experimental setups.     

Natural hormone patterns of meat from steers and bulls depending on slaughter age

 Natural patterns of steroid hormones (androgens, progestogens and corticoids), their precursors and metabolites were analysed in 48 beef samples with gas chromatography-mass spectrometry (GC-MS). Muscle tissue samples were taken from steers (n=23) and bulls (n=25) of the breed German Simmental, which were slaughtered at different ages (151–705 days of age). Concentrations of testosterone, dehydroepiandrosterone (DHEA), progesterone, cortisol and cortisone in beef from steers were not dependent on age, whereas pregnenolone, androstenedione and epitestosterone increased significantly with increasing slaughter age (r=0.48, P<0.05;r=0.60, P<0.01 and r=0.62, P<0.001, respectively). The concentrations of the metabolite androsterone tended to increase as well. The differences were not significant, however, due to the high level of variability. In beef from bulls cortisone concentrations were inversely correlated with increasing slaughter age (r=–0.47, P<0.05). The decrease from day 175 to day 260 was significant. Testosterone was positively correlated with increasing age (r=0.46, P<0.05). The tissue concentrations at the different slaughter ages did not differ significantly, however. The Δ5-precursors pregnenolone and DHEA tended to show a minimum at the age of 370 days, followed by a significant increase. No age dependence of the progesterone, androstenedione, androsterone, epitestosterone and cortisol concentrations could be detected. Analysis of steroid hormone concentrations may form part of a reliable method for estimating the age of slaughtered cattle. In this study, the age of samples was estimated to within ± an average of 10 weeks. Received: 29 December 1997 / Revised version: 1 March 1998     

抑制微溶盐在供水过程中沉淀

本发明提供了一种通过抑制垢在供水过程中沉淀防止含水系统中垢沉淀的方法和装置,该装置包括：（1）一种电解电池流动连接到该系统,包括①接收供水的槽,该槽中的铜表面形成一种电池阴极;②在槽内具有被处理后的锌表面的元件,并且形成电池的阳极;（2）一种控制设备用于控制来自电源的电流（I）;（3）一个流量计,用于测量供水流速与进入系统的水流速有关的流速,其中控制设备被设计用于根据流速控制电流,     

Modeling psychotherapy outcome as an event in time: An application of multistage analysis.

Standard survival analysis (SA) and multistate analysis (MSA) are methods for modeling categorical psychotherapy outcome events over time. The underlying principles, mathematical details, and indications for using each technique are discussed, and data from an anorexia nervosa psychotherapy outcome study comparing psychodynamic psychotherapy with psychodynamic psychotherapy plus cognitive–behavioral techniques are used to illustrate the use of SA and MSA techniques. MSA includes multiple competing outcome states in a single model. A single MSA model includes reaching target weight and treatment dropout before reaching target weight as competing events. It is concluded that MSA is an informative analytic technique in the domain of psychotherapy research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)