Algorithm for multi-curve-fitting with shared parameters and a possible application in evoked compound action potential measurements

BACKGROUND: Experimental results are commonly fitted by determining parameter values of suitable mathematical expressions. In case a relation exists between different data sets, the accuracy of the parameters obtained can be increased by incorporating this relationship in the fitting process instead of fitting the recordings separately. METHODS: An algorithm to fit multiple measured curves simultaneously was developed. The method accounts for parameters that are shared by some curves. It can be applied to either linear or nonlinear equations. Simulated noisy "measurement results" were created to compare the introduced method to the "straight forward" way of fitting the curves separately. RESULTS: The analysis of the simulated measurements confirm, that the introduced method yields more accurate parameters compared to the ones gained by fitting the measurements separately. Therefore it needs more computer time. As an example, the new fitting algorithm is applied to the measurements of the evoked compound action potentials (ECAP) of the auditory nerve: This leads to promising ideas to reduce artefacts generated by the measuring process. CONCLUSION: The introduced fitting algorithm uses the relationship between multiple measurement results to increase the accuracy of the parameters. Its application in the field of ECAP measurements is promising and should be further investigated

Project-based learning - area of improving the quality of school

U traženju najboljih načina za ostvarivanje ciljeva nastave, jedno od mogućih didaktičkih rješenja pronalazimo u projektnoj nastavi. Ravitz i sur. (2012) opisuju projektnu nastavu kao koncept stvaranja uvjeta u kojima učenici mogu učiti složenija znanja i vještine koja su im nepohodna za život u 21. stoljeću. Ona predstavlja brojne izazove za učitelje i škole, a poteškoće na koje nailaze pri njezinoj implementaciji su brojne. Za učinkovito rješavanje problema implementacije projektne nastave u radu škole, neophodno je omogućiti učiteljima samovrednovanje nastavnog procesa. Samovrednovanje je proces koji sustavno prati, analizira i procjenjuje uspješnost rada kako bi se trajno unaprijedila kvaliteta i stvorilo poticajno radno okruženje. U ovom je radu prikazan primjer Školskog razvojnog plana, kao sastavnog dijela procesa samovrednovanja, kojim je projektna nastava definirana kao prioritetno područje unaprjeđenja rada škole i razvojnih ciljeva koji proizlaze iz njih.In finding the best ways to accomplish learning goals one of the possible didactic solutions would be project-based learning. Ravitz et al. (2012) describe project-based learning as a concept that involves creating conditions which would help students learn more complex knowledge and skills vital for the life in the 21st century. This concept holds many challenges for both teachers and schools, and many issues arise in its implementation. The effective solution for the implementation problems of project-based learning in schools necessary involves self-evaluation of the teaching process. Self-evaluation is a process that systematically monitors, analyses and assesses the work performance in order to permanently achieve better quality and create a more productive working surroundings. This paper shows an example of a school development plan, as an integral part of the self-evaluation process, that defines the project-based learning as a priority area in improving the school processes and development goals which derive from them

Multitrophic Interaction in the Rhizosphere of Maize: Root Feeding of Western Corn Rootworm Larvae Alters the Microbial Community Composition

BACKGROUND: Larvae of the Western Corn Rootworm (WCR) feeding on maize roots cause heavy economical losses in the US and in Europe. New or adapted pest management strategies urgently require a better understanding of the multitrophic interaction in the rhizosphere. This study aimed to investigate the effect of WCR root feeding on the microbial communities colonizing the maize rhizosphere. METHODOLOGY/PRINCIPAL FINDINGS: In a greenhouse experiment, maize lines KWS13, KWS14, KWS15 and MON88017 were grown in three different soil types in presence and in absence of WCR larvae. Bacterial and fungal community structures were analyzed by denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene and ITS fragments, PCR amplified from the total rhizosphere community DNA. DGGE bands with increased intensity were excised from the gel, cloned and sequenced in order to identify specific bacteria responding to WCR larval feeding. DGGE fingerprints showed that the soil type and the maize line influenced the fungal and bacterial communities inhabiting the maize rhizosphere. WCR larval feeding affected the rhiyosphere microbial populations in a soil type and maize line dependent manner. DGGE band sequencing revealed an increased abundance of Acinetobacter calcoaceticus in the rhizosphere of several maize lines in all soil types upon WCR larval feeding. CONCLUSION/SIGNIFICANCE: The effects of both rhizosphere and WCR larval feeding seemed to be stronger on bacterial communities than on fungi. Bacterial and fungal community shifts in response to larval feeding were most likely due to changes of root exudation patterns. The increased abundance of A. calcoaceticus suggested that phenolic compounds were released upon WCR wounding

Fast Feedback Control over Multi-hop Wireless Networks with Mode Changes and Stability Guarantees

Closing feedback loops fast and over long distances is key to emerging cyber-physical applications; for example, robot motion control and swarm coordination require update intervals of tens of milliseconds. Low-power wireless communication technology is preferred for its low cost, small form factor, and flexibility, especially if the devices support multi-hop communication. Thus far, however, feedback control over multi-hop low-power wireless networks has only been demonstrated for update intervals on the order of seconds. To fill this gap, this paper presents a wireless embedded system that supports dynamic mode changes and tames imperfections impairing control performance (e.g., jitter and message loss), and a control design that exploits the essential properties of this system to provably guarantee closed-loop stability for physical processes with linear time-invariant dynamics in the presence of mode changes. Using experiments on a cyber-physical testbed with 20 wireless devices and multiple cart-pole systems, we are the first to demonstrate and evaluate feedback control and coordination with mode changes over multi-hop networks for update intervals of 20 to 50 milliseconds.Comment: Accepted for publication in ACM Transactions on Cyber-Physical Systems. arXiv admin note: text overlap with arXiv:1804.0898

Co-metabolic formation of substituted phenylacetic acids by styrene-degrading bacteria

Some soil bacteria are able to metabolize styrene via initial side-chain oxygenation. This catabolic route is of potential biotechnological relevance due to the occurrence of phenylacetic acid as a central metabolite. The styrene-degrading strains Rhodococcus opacus 1CP, Pseudomonas fluorescens ST, and the novel isolates Sphingopyxis sp. Kp5.2 and Gordonia sp. CWB2 were investigated with respect to their applicability to co-metabolically produce substituted phenylacetic acids. Isolates were found to differ significantly in substrate tolerance and biotransformation yields. Especially, P. fluorescens ST was identified as a promising candidate for the production of several phenylacetic acids. The biotransformation of 4-chlorostyrene with cells of strain ST was shown to be stable over a period of more than 200 days and yielded about 38 mmolproduct gcelldryweight−1 after nearly 350 days. Moreover, 4-chloro-α-methylstyrene was predominantly converted to the (S)-enantiomer of the acid with 40% enantiomeric excess

Mallard Use of Hen HousesTM in Eastern Ontario

Nesting structures for ground-nesting waterfowl may be an effective technique for increasing nesting success in regions in which nest success is below the 15% threshold needed to maintain a stable population. We studied the occupancy rate of artificial nesting structures called hen housesTM by Mallards (Anas platyrhynchos) nesting in two different wetland habitats, beaver ponds and sewage lagoons, in eastern Ontario during 1999-2001. We hypothesized that, because natural cover was sparse on sewage lagoons, Mallards would occupy hen houses at a higher rate on sewage lagoons than on beaver ponds. However, of the 248 hen houses distributed between beaver ponds and sewage lagoons, none was occupied by waterfowl. Common Grackles (Quiscalus quiscula) were the only avian species that nested in hen houses. However, Mallards successfully nested directly under several structures (n = 6) when water levels were low enough to expose the ground beneath them. Mayfield daily nest survival estimates for Mallards nesting in natural cover were similar on sewage lagoons and beaver ponds for all years (mean = 0.99) and were higher than most published estimates. Factors such as nesting cover, predation pressures, and structure design and material may influence the use of artificial hen houses and should be considered when planning a hen house program outside of the Prairie Pothole Region

Mallard Use of Hen Houses TM in Eastern Ontario Utilisation de nichoirs de type hen house MD par le Canard colvert dans l'est de l'Ontario

ABSTRACT. Nesting structures for ground-nesting waterfowl may be an effective technique for increasing nesting success in regions in which nest success is below the 15% threshold needed to maintain a stable population. We studied the occupancy rate of artificial nesting structures called hen houses TM by Mallards (Anas platyrhynchos) nesting in two different wetland habitats, beaver ponds and sewage lagoons, in eastern Ontario during 1999-2001. We hypothesized that, because natural cover was sparse on sewage lagoons, Mallards would occupy hen houses at a higher rate on sewage lagoons than on beaver ponds. However, of the 248 hen houses distributed between beaver ponds and sewage lagoons, none was occupied by waterfowl. Common Grackles (Quiscalus quiscula) were the only avian species that nested in hen houses. However, Mallards successfully nested directly under several structures (n = 6) when water levels were low enough to expose the ground beneath them. Mayfield daily nest survival estimates for Mallards nesting in natural cover were similar on sewage lagoons and beaver ponds for all years (mean = 0.99) and were higher than most published estimates. Factors such as nesting cover, predation pressures, and structure design and material may influence the use of artificial hen houses and should be considered when planning a hen house program outside of the Prairie Pothole Region. RÉSUMÉ. Des nichoirs conçus pour les espèces de sauvagine nichant sur le sol peuvent s'avérer une technique efficace pour accroître le succès de la reproduction dans les régions où ce succès est inférieur au seuil de 15 % nécessaire au maintien d'une population stable. Pendant la période de 1999 à 2001, nous avons étudié le taux d'occupation de structures de nidification artificielles appelées hen house MD par les Canards colverts (Anas platyrhynchos) nichant dans deux types d'habitats humides de l'est de l'Ontario, soit des étangs de castor et des bassins de stabilisation des eaux usées. Nous avons émis l'hypothèse selon laquelle la proportion de nichoirs occupés par le Canard colvert serait plus élevée dans les bassins de stabilisation que dans les étangs de castor parce que le couvert naturel était plus clairsemé dans les bassins. Cependant, aucun des 248 nichoirs répartis entre les étangs de castor et les bassins de stabilisation des eaux usées n'a été occupé par la sauvagine. Le Quiscale bronzé (Quiscalus quiscula) est la seule espèce aviaire qui a utilisé ces nichoirs. Cependant, le Canard colvert s'est reproduit avec succès sous plusieurs de ces structures (n = 6) quand les niveaux d'eau étaient suffisamment bas pour que le sol sous-jacent soit exposé. Chez les Canards colverts nichant dans des microhabitats naturels, les estimations du taux journalier de survie au nid selon la méthode de Mayfield étaient très similaires dans les bassins de stabilisation et les étangs de castor pour toutes les années (moyenne = 0,99) et supérieures à la plupart des valeurs publiées. Des facteurs comme le degré de couvert végétal au nid, la pression exercée par les prédateurs ainsi que la conception de la structure et les matériaux utilisés peuvent avoir une incidence sur l'utilisation de nichoirs à canard et devraient être pris en compte dans la planification d'un programme d'installation de nichoirs hen house en dehors de la région des cuvettes des Prairies

Does the foveal shape influence the image formation in human eyes?

In human eyes, the maximum visual acuity correlates locally with the fovea, a shallow depression in the retina. Previous examinations have been reduced to simple geometrical fovea models derived from postmortem preparations and considering only a few superficial ray propagation aspects. In the current study, an extended and realistic analysis of ray-optical simulations for a comprehensive anatomical realistic eye model for the anterior part and realistic aspherical human foveal topographical profiles deduced from in vivo optical coherence tomography (OCT) are presented, and the refractive index step at the transition from vitreous to retinal tissue is taken into account. The optical effect of a commonly shaped (averaged) and an extraordinarily shaped foveal pit were both compared to the analysis of an assumed pure spherical boundary layer. The influence of the aperture size, wavelength, and incident angle on the spot size and shape, as well as the axial focal and latera l centroid position is investigated, and a lateral displacement of about 2 μm and an axial shift of the best focal position of less than 4 μm are found. These findings indicate only small optical effects that are laterally in the range of inter-receptor distances and axially less than the photoreceptor outer segment dimension