Fractional-order viscoelasticity applied to describe uniaxial stress relaxation of human arteries.

Viscoelastic models can be used to better understand arterial wall mechanics in physiological and pathological conditions. The arterial wall reveals very slow time-dependent decays in uniaxial stress-relaxation experiments, coherent with weak power-law functions. Quasi-linear viscoelastic (QLV) theory was successfully applied to modeling such responses, but an accurate estimation of the reduced relaxation function parameters can be very difficult. In this work, an alternative relaxation function based on fractional calculus theory is proposed to describe stress relaxation experiments in strips cut from healthy human aortas. Stress relaxation (1 h) was registered at three incremental stress levels. The novel relaxation function with three parameters was integrated into the QLV theory to fit experimental data. It was based in a modified Voigt model, including a fractional element of order α, called spring–pot. The stressrelaxation predictionwas accurate and fast. Sensitivity plots for each parameter presented a minimum near their optimal values. Least-squares errors remained below 2%. Values of order α = 0.1–0.3 confirmed a predominant elastic behavior. The other two parameters of the model can be associated to elastic and viscous constants that explain the time course of the observed relaxation function. The fractional-order model integrated into the QLV theory proved to capture the essential features of the arterial wall mechanical response

Early Detection of Critical Pulmonary Shunts in Infants

This paper aims to improve the design of modern Medical Cyber Physical Systems through the addition of supplemental noninvasive monitors. Specifically, we focus on monitoring the arterial blood oxygen content (CaO2), one of the most closely observed vital signs in operating rooms, currently measured by a proxy - peripheral hemoglobin oxygen saturation (SpO2). While SpO2 is a good estimate of O2 content in the finger where it is measured, it is a delayed measure of its content in the arteries. In addition, it does not incorporate system dynamics and is a poor predictor of future CaO2 values. Therefore, as a first step towards supplementing the usage of SpO2, this work introduces a predictive monitor designed to provide early detection of critical drops in CaO2 caused by a pulmonary shunt in infants. To this end, we develop a formal model of the circulation of oxygen and carbon dioxide in the body, characterized by unknown patient-unique parameters. Employing the model, we design a matched subspace detector to provide a near constant false alarm rate invariant to these parameters and modeling uncertainties. Finally, we validate our approach on real-patient data from lung lobectomy surgeries performed at the Children\u27s Hospital of Philadelphia. Given 198 infants, the detector predicted 81% of the critical drops in CaO2 at an average of about 65 seconds earlier than the SpO2-based monitor, while achieving a 0:9% false alarm rate (representing about 2 false alarms per hour)

Harvesting Electricity with Geobacter bremensis Isolated from Compost

Electrochemically active (EA) biofilms were formed on metallic dimensionally stable anode-type electrode (DSA), embedded in garden compost and polarized at +0.50 V/SCE. Analysis of 16S rRNA gene libraries revealed that biofilms were heavily enriched in Deltaproteobacteria in comparison to control biofilms formed on non-polarized electrodes, which were preferentially composed of Gammaproteobacteria and Firmicutes. Among Deltaproteobacteria, sequences affiliated with Pelobacter and Geobacter genera were identified. A bacterial consortium was cultivated, in which 25 isolates were identified as Geobacter bremensis. Pure cultures of 4 different G. bremensis isolates gave higher current densities (1400 mA/m2 on DSA, 2490 mA/m2 on graphite) than the original multi-species biofilms (in average 300 mA/m2 on DSA) and the G. bremensis DSM type strain (100–300 A/m2 on DSA; 2485 mA/m2 on graphite). FISH analysis confirmed that G. bremensis represented a minor fraction in the original EA biofilm, in which species related to Pelobacter genus were predominant. The Pelobacter type strain did not show EA capacity, which can explain the lower performance of the multi-species biofilms. These results stressed the great interest of extracting and culturing pure EA strains from wild EA biofilms to improve the current density provided by microbial anodes

Microbial Fuel Cells and Microbial Ecology: Applications in Ruminant Health and Production Research

Microbial fuel cell (MFC) systems employ the catalytic activity of microbes to produce electricity from the oxidation of organic, and in some cases inorganic, substrates. MFC systems have been primarily explored for their use in bioremediation and bioenergy applications; however, these systems also offer a unique strategy for the cultivation of synergistic microbial communities. It has been hypothesized that the mechanism(s) of microbial electron transfer that enable electricity production in MFCs may be a cooperative strategy within mixed microbial consortia that is associated with, or is an alternative to, interspecies hydrogen (H2) transfer. Microbial fermentation processes and methanogenesis in ruminant animals are highly dependent on the consumption and production of H2in the rumen. Given the crucial role that H2 plays in ruminant digestion, it is desirable to understand the microbial relationships that control H2 partial pressures within the rumen; MFCs may serve as unique tools for studying this complex ecological system. Further, MFC systems offer a novel approach to studying biofilms that form under different redox conditions and may be applied to achieve a greater understanding of how microbial biofilms impact animal health. Here, we present a brief summary of the efforts made towards understanding rumen microbial ecology, microbial biofilms related to animal health, and how MFCs may be further applied in ruminant research

Turbidity of water provided by the water supply systems in the Malopolskie Voivodeship.

W pracy dokonano analizy mętności wody dostarczonej odbiorcom w 2007 r. przez systemy wodociągowe w województwie małopolskim. W analizie uwzględniono wszystkie zakłady wodociągowe, które są objęte monitoringiem kontrolnym i przeglądowym przez wojewódzkie służby sanitarno-epidemiologiczne - łącznie 703. W badaniach obejmujących analizę 1794 próbek wody, w tym 167 próbek wody powierzchniowej, 1261 - wody podziemnej i 366 - wody mieszanej, określono mętność minimalną, maksymalną i średnią oraz liczbę przekroczeń mętności dopuszczalnej (1 NTU). Przeprowadzona analiza wykazała, że mętność wody wodociągowej, w zależności od źródła wody, wynosiła: wody powierzchniowe 0,1÷8,7 NTU (śr. 0,97 NTU), wody podziemne 0,01÷26,0 NTU (śr. 0,84 NTU), wody mieszane 0,02÷10,0 NTU (śr. 0,93 NTU). Najwięcej przekroczeń mętności dopuszczalnej odnotowano w wodociągach korzystających z wód powierzchniowych - 29,3% analizowanych próbek, a znacznie mniej w korzystających z wód podziemnych - 12,4% i mieszanych - 4,1%. Przekroczenia te w przeważającej większości przypadków mieściły się w przedziale 1÷5 NTU.The water supplied to the users in the Malopolskie Voivodeship in 2007 was analyzed for turbidity. The analysis covered 703 waterworks regularly monitored by the Regional Sanitary and Epidemiological Station. A total of 1794 water samples was made subject to analysis (167 surface water samples, 1261 groundwater samples and 366 mixed water samples) to determine the minimal, maximal and average turbidity levels, as well as the number of episodes when the admissible turbidity value (1 NTU) was exceeded. The study has produced the following findings. According to the water source being used, the turbidity of the tap water supplied varied from 0.1 to 8.7 NTU (av. 0.97 NTU) for surface water, from 0.01 to 26.0 NTU (av. 0.84 NTU) for groundwater, and from 0.02 to 10.0 NTU (av. 0.93 NTU) for mixed water. The majority of episodes with the 1 NTU value being exceeded were observed in the waterworks using surface water (29.3% of samples). Significantly lower was the number of such episodes in the waterworks where use was made of groundwater (12.4% of samples) or mixed water (4.1% of samples). In most instances the exceeded turbidity values were within the range of 1 to 5 NTU